J.8_U.S. Tower Manual_COMDTINST M11000.4.pdf

TOWER MANUAL

COMDTINST M11000.4A

JANUARY 2002

DISTRIBUTION – SDL No. 139 a b c d e f g h i j k l m n o p q r s t u v w x y z

A B * 2 5 2 2 1 2 2 2 30 10 20 10 C 2 10* 2 2 5 2 1

COMDTINST M11000.4A

Commandant United States Coast Guard

2100 Second Street, S.W.

Washington, DC 20593-0001 Staff Symbol: G-S Phone: (202) 267-6031

FAX: (202) 267-4219

JAN 11 2002

COMMANDANT INSTRUCTION M11000.4A

Subj: TOWER MANUAL

1. PURPOSE. This Manual defines Coast Guard policy and criteria for the preservation of towers and prescribes minimum inspection and maintenance standards for use as a guide in organizing and managing a comprehensive tower inspection and maintenance program.

2. ACTION. Commanders of Maintenance and Logistics Commands shall ensure that the provisions of this Manual are followed. Internet release is authorized.

3. DIRECTIVES AFFECTED. The Tower Manual, COMDTINST M11000.4, is cancelled.

4. DISCUSSION. The previous edition of the Tower Manual, COMDTINST M11000.4A, was written in 1978 with the last changes made in 1982. Although much of the information in the manual was applicable to the current tower program, the manual primarily addressed tall guyed towers, specifically OMEGA and LORAN. The Coast Guard's tower inventory is growing annually and has changed significantly over the past 20 years. The majority of Coast Guard towers today are small towers under 300ft that received only cursory attention in the previous edition. Secondly, safety requirements and equipment have also improved steadily and the most significant change to this revision is in the tower safety chapter. Due to the large volume of new information and required changes, the old Tower Manual, COMDTINST M11000.4, is cancelled in its entirety. The new Tower Manual, COMDTINST M11000.4A, has been reorganized and streamlined for quicker and easier access to information.

5. MAJOR CHANGES. Major changes from the previous version of the Manual include: new tower definitions, more detailed requirements for tower safety, establishment of Tall Tower Coordination Center, new recommended inspection routines and items, updated tower failure information, incorporated portions of various unit level small tower handbooks, new information on antenna installation and removal, eliminated dated information relating to OMEGA and ACTEUR towers, new information on tower marking systems in accordance with latest FAA Advisory Circulars, new information on alignment and twist methods, updated information on guy tension methods, D 5 E 2 F G H NON-STANDARD DISTRIBUTION: B:a G-S (5), G-O (5); C:g CEU OAKLAND (30)

COMDTINST M11000.4ACOMDTINST M11000.4A

established new recommended formats for tower inspection reports for both small and tall towers, and updated information on LORAN base insulator replacements.

REQUEST FOR CHANGES. Units and individuals may recommend changes by writing via the chain of command to Commandant (G-SEC), U.S. Coast Guard Headquarters, Washington, DC 20593-0001.

R. F. SILVA

ASSISTANT COMMANDANT FOR SYSTEMS

“CHIEF ENGINEER”

TABLE OF CONTENTS

TABLE OF CONTENTS........................................................... i

CHAPTER 1. INTRODUCTION.................................................. 1-1

A. Purpose and Scope.......................................... 1-1 B. Responsibilities........................................... 1-1 C. Inspection and Maintenance Standards and Costs............. 1-1 D. Revision of Manual......................................... 1-1

CHAPTER 2. TOWER SAFETY.................................................. 2-1

PART I. GENERAL CLIMBING SAFETY ................................. 2-1

A. Safety Policy and Requirements............................. 2-1 B. Buddy System............................................... 2-1 C. Climbing of Towers by Coast Guard Personnel................ 2-1 D. Minimum Requirements....................................... 2-2 E. Equipment.................................................. 2-2 F. Pre-Climb Safety........................................... 2-5 G. Conditioning and Mechanics of Climbing..................... 2-6 H. Rescue..................................................... 2-7

PART II. GENERAL TOWER SAFETY ................................... 2-8

A. Climbing of Towers by Contractor........................... 2-8 B. Work on Energized Towers................................... 2-8 C. Maintenance of Energized Towers............................ 2-9 D. Ladders and Safety Climbing Devices........................ 2-9 E. Protective Barriers and Warning Signs..................... 2-10

CHAPTER 3. INSPECTION GUIDELINES......................................... 3-1

A. General.................................................... 3-1 B. Inspection Categories...................................... 3-1 C. Inspection Objectives and Requirements..................... 3-2 D. Tower Failures............................................. 3-7

CHAPTER 4. MAINTENANCE GUIDELINES........................................ 4-1

A. Maintenance Objectives and Requirements.................... 4-1 B. Maintenance, Repair, and Modification...................... 4-3 C. General Inspection and Maintenance Problems................ 4-4 D. Common Abnormalities....................................... 4-8 E. Replacement of Structural Members......................... 4-11

CHAPTER 5. TOWER STRUCTURE............................................... 5-1

A. General.................................................... 5-1 B. Standard Tower Leg and Face Designations................... 5-1 C. Structural Members......................................... 5-1 D. Base Insulators........................................... 5-10 E. Tower Base................................................ 5-13 F. Ladder Safety Rail, and Rest Platforms.................... 5-16 G. Hoists and Elevators...................................... 5-16 H. Ground Systems............................................ 5-16 I. Tower Jacking Legs........................................ 5-17 J. Spare Parts............................................... 5-17 K. Antenna Installations..................................... 5-18 L. Antenna Removals.......................................... 5-18

CHAPTER 6. GUYS AND GUY ANCHORS.......................................... 6-1

A. General.................................................... 6-1 B. Standard Guys, Guy Anchor and Insulator Designations....... 6-1 C. Guy Cables and End Fittings................................ 6-3 D. Wire Strand and Rope....................................... 6-3 E. Galvanized Steel Cable..................................... 6-6 F. Aluminum Coated Steel Cable................................ 6-6 i

G. Reinforced Aluminum Conductors............................. 6-6 H. Copper Coated Steel Cable.................................. 6-7 I. Cable End Fittings......................................... 6-7 J. Inspection and Maintenance................................ 6-10 K. Guy Cable Hardware........................................ 6-13 L. Insulators................................................ 6-17 M. Gradient Cones and Arcing Rings........................... 6-25 N. Tower Anchors............................................. 6-26 O. Tower Guy Accessories..................................... 6-28

CHAPTER 7. TOWER PAINTING................................................ 7-1

A. General.................................................... 7-1 B. Maintenance of Tower Painting.............................. 7-2 C. Standard Tower Painting Systems............................ 7-3 D. Alternative Painting Systems............................... 7-4 E. Corrosion Protection of Unpainted Towers................... 7-4 F. Ladders and Safety Rails................................... 7-5 G. Application................................................ 7-5 H. Records.................................................... 7-5

CHAPTER 8. TOWER ERECTION, ALIGNMENT, TWIST, AND GUY TENSIONS............ 8-1

A. General.................................................... 8-1 B. General Tower Design Characteristics....................... 8-1 C. Analysis of Existing Towers................................ 8-2 D. Cause of Misalignment and Twist............................ 8-2 E. Alignment, Twist and Guy Tension Limitations............... 8-2 F. Conditions for Alignment, Twist, and Tension Measurements.. 8-3 G. Determination of Alignment and Twist....................... 8-4 H. Guy Tensions.............................................. 8-13 I. Correction of Alignment and Guy Tension................... 8-19 J. Frequency and Scope of Alignment and Tension Checks....... 8-20

CHAPTER 9. TOWER LIGHTING AND LIGHTNING PROTECTION....................... 9-1

A. General.................................................... 9-1 B. FAA Notification Requirements for Tower Lighting Failures.. 9-1 C. Tower Lighting System Components........................... 9-1 D. New Lighting System Requirements........................... 9-5 E. Lighting System Inspection and Maintenance................. 9-5 F. Lightning Protection....................................... 9-7

APPENDIX A. GLOSSARY

APPENDIX B. INSPECTION FORMS

APPENDIX C. MANUFACTURER'S DATA FOR VARIOUS TOWER COMPONENTS

APPENDIX D. LORAN BASE INSULATOR REPLACEMENT

APPENDIX E. SPECIAL EVOLUTIONS FOR LORAN TOWERS

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CHAPTER 1. INTRODUCTION

A. Purpose and Scope. This Manual defines Coast Guard policy and criteria for the preservation of towers and prescribes minimum inspection and maintenance standards for use as a guide in organizing and managing a comprehensive tower inspection and maintenance program. The primary objectives of such a program are to keep critical antenna and navigation systems operational to the maximum possible extent, and to protect the Government's investment by economically maintaining the towers. This Manual shall be utilized for all Coast Guard towers to the maximum feasible extent. Towers are defined as any permanent structure that is more vertical than horizontal, that is energized or non-energized, guyed or free standing, and exceeds 20 feet in height. Tall towers are those 300ft in height or greater. Small towers are those less than 300ft in height. The safety requirements in Chapter Two of this Manual are applicable to all towers and elevated structures including monopoles, ATON structures, and communications support structures.

B. Responsibilities. Commanding Officers of Civil Engineering Units are responsible for the establishment, administration, and direction of an inspection and maintenance program for the towers under their jurisdiction. To be effective, a sound inspection and maintenance program requires delegation of responsibilities and the full and continued support of all concerned. Therefore, a channel of clearly fixed responsibility for tower inspection and maintenance shall be established from the Civil Engineering Unit (CEU) to other commands in the field. Civil Engineering Units shall ensure, through directives, reports, etc., that the program is aggressively carried out at all levels in a systematic and thoroughly acceptable manner. Towers shall be periodically inspected by the various command levels to evaluate the sufficiency and consistency of the overall inspection and maintenance effort, and to verify attainment of the established standards of maintenance.

C. Inspection and Maintenance Standards and Costs. Since differences in tower designs, materials, age, local environment, and previous maintenance are some of the factors of the inspection and maintenance program, standards shall be established by the servicing CEU within the latitude permitted by this Manual. These standards should be developed to permit timely detection and correction of deficiencies in order to preclude the necessity for major repairs or complete tower replacement.

The frequency and extent of inspection and maintenance activities will be governed by the effort necessary to maintain the towers at the level of these standards. The effort to keep energized antenna tower off-air time to a minimum may necessitate increased costs for tower maintenance; a responsible trade-off must be made between cost and operating time. In general, CEUs should plan their inspections and maintenance of energized towers so that cost is a factor that is of less importance than off-air time. However, it is not intended that our structures be over-maintained at undue cost; judgment must be exercised at all times. In most cases, the final decision should be made by the servicing CEU, preferably within field budget limitations.

D. Revision of Manual. This Manual will be updated periodically. Civil

Engineering Units and other tower units are encouraged to provide the

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Coast Guard Tower Program Coordination Center (CEU Oakland) with information copies of all tower-related reports, correspondence, and similar material which describe program improvements and practices of potential use to other commands. Field input remains the primary source of material for this Manual.

Figure 1-1 700ft energized Loran-C tower.

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Figure 1-2 90ft Self supporting Vessel Traffic System tower.

Figure 1-3 Self supporting microwave tower.

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Figure 1-4 60ft Self supporting communications tower.

Figure 1-5 Guyed rotatable antenna

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CHAPTER 2. TOWER SAFETY

This chapter is divided into two sections; Part I is General Climbing Safety.

Part II is General Tower Safety.

PART I. GENERAL CLIMBING SAFETY

A. Safety Policy and Requirements. Safety is a primary consideration to which all Coast Guard personnel must devote their complete attention whenever they are climbing a tower or are in the immediate vicinity of a tower of any height. The elevation and potential electrical hazards associated with tower inspection, maintenance, and repair require adoption of extraordinary safety measures in order to protect the climbers from avoidable accidents. Towers are classified as elevated structures as defined by OSHA. All personnel engaging in construction, maintenance, repair or inspection shall use fall protection when working on any Coast Guard tower. Safety precautions also include the use of appropriate protective clothing to include the wearing of safety helmets, safety footwear, eye protection, and protective clothing to protect personnel from injury while in the vicinity of a tower. A safety helmet is required to be worn by any person within the tower drop zone, which is an area whose radius is 1/2 the height of the tower and centered on the tower axis. In addition, precautionary measures must be taken to protect the tower structure itself from damage.

B. Buddy System. Climbers shall use the buddy system. When climbing to a height of 150ft or less a safety observer is required on the ground. The observer should be stationed a suitable distance away from the tower base, preferably upwind, so that he or she always has a clear view of the climber. The safety observer shall be a qualified climber who meets the requirements of D below. The safety observer shall be completely dressed with appropriate Personal Protective Equipment (PPE) including a Personal Fall Arrest System (PFAS) and a complete safety ladder climbing device. The safety observer shall have constant two-way communication with the climber on the tower. When climbing towers greater than 150ft in height the safety observer shall join the primary climber on the tower and stay within 150ft of the primary climber at all times.

C. Climbing of Towers by Coast Guard Personnel. Coast Guard personnel must be authorized in writing to climb towers and elevated structures. This specifically includes all towers and elevated structures classified as Aids to Navigation. The servicing CEU has the authority to administer the Tower Climber Certification program for all units within its area of responsibility (AOR). At a minimum, the prospective climber shall have adequate knowledge of the following subjects:

1. Recognition and avoidance of dangers relating to encounters with harmful substances and animal, insect, or plant life.

2. Use and inspection of personal fall-arrest equipment.

3. Procedures to be followed in emergency situations.

4. Rescue procedures.

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5. First aid training including CPR - These requirements are not specifically taught in a tower qualification course. The tower program specifically relies on the PQS standards that require annual basic first aid. CPR training is highly recommended for all climbers.

D. Minimum Requirements. The following are the minimum requirements to qualify an individual to climb elevated structures.

1. The climber must be a responsible volunteer.

2. The climber must be physically qualified and physically capable.

3. The unit commander must recommend the climber.

4. The climber must complete climbing certification training, which includes a written test and a practical field test.

5. On the first climb the climber must be accompanied by a qualified

Coast Guard military or civilian engineer who has been certified to instruct tower climbing and who is familiar with the safety requirements and hazards outlined in this Manual.

6. The climber shall be issued a written qualification letter from the servicing CEU. This letter will specify the maximum height of tower that the individual is authorized to climb and whether the individual is authorized to climb an energized or non-energized tower. This letter remains in effect as long as the climber remains within the AOR of the CEU that issued the letter.

E. Equipment. The equipment requirements are specifically referenced in

OSHA 1926.502(d).

1. The climber must use a complete Personal Fall Arrest System,(PFAS), which consists at a minimum of a full body harness, deceleration lanyard(s), and connecting device(s). In addition when using a ladder for ascent or descent, the climber shall use a ladder safety climbing device, as shown in Figure 2-3. Climbers shall be physically connected to suitable anchorage on the structure at all times. See Part II D of this chapter, and Figures 2-1 and 2-2.

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Figure 2-1 Existing Coast Guard Harnesses (front and rear view).

Figure 2-2 Typical commercial harness meeting ANSI requirements.

2. All Personal Protective Equipment used must meet the standards of 29 CFR 1926.502, Fall Protection System Criteria and Practices, Subpart M, Fall Protection.

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a. Personal Fall Arrest Systems consist at minimum of an anchorage, full body harness, deceleration lanyard and connecting device.

(1) Anchorages are secure points of attachment for lifelines, lanyards or deceleration devices, and are independent from the means supporting the worker.

(2) Full body harness must meet ANSI Z359.1-1992 requirements and must have a "D" ring which is centered in the wearer's upper back. The harness must be sized to the individual. The full body harness must be specifically rated for fall arrest (see Figures 2-1 and 2-2).

(3) Connecting devices include deceleration lanyards, working lanyards and ladder safety climbing device. Shock absorbing fall restraint lanyards (also called deceleration lanyards) must meet ANSI Z359.1-1992 and ANSI A10.14-1991. These devices limit free-fall to 6 ft. The shock absorbing portion of the lanyard must be attached closest to the wearer's body. The overall length of the lanyard is limited to 6ft. Ropes, straps and webbing used in lanyards, lifelines and strength components of body harnesses shall be made from synthetic fibers.

b. Connecting Hardware must have double-acting or 2-step safety locks. Shackles, clevis, carabiners, and hooks are the four common hardware connecting devices. All connecting hardware must have a minimum tensile strength of 5000 pounds and shall be proof tested to a minimum of 3600 pounds.

Figure 2-3 Typical ladder safety climbing device (Saf-T-Climb).

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c. No part of a personal fall arrest system shall be used for other than its intended purpose. Never use this equipment for hoisting or towing. Do not use this equipment for recreational climbing.

d. Understand, know and follow the maximum weight limits for your personal fall arrest safety equipment. These limits are stated in the manufacturer's instructions. The working load limit is equal to the combined person and tool weight. Generally, the working load limit for a full body harness is 310 pounds.

e. All equipment, lines and hardware shall be rated for use. Each piece of equipment shall be inspected for wear, damage, and other deterioration before each use, and defective components shall be immediately removed from service and destroyed.

F. Pre-Climb Safety. Pre-mobilization planning; Prior to any work on an elevated structure the following shall be evaluated by the supervisor:

1. The skill and experience of each member of the crew assigned to perform the work.

2. Any special equipment that will need to be acquired and any special training or training reviews that must be performed before work begins.

3. The type of equipment that will be required and the individual worker's training and skill with that equipment.

4. Any special fabrication required for safety before work begins.

5. The emergency services available near the site and whether they could find the site in a timely manner. Question rescue services to establish that they have the equipment, skills and response time to rescue a climber in the expected environment. These services should be given directions to the site.

6. The location of the nearest medical facilities. Every member of the crew should have access to a route map.

7. The phone numbers of emergency facilities, accessible to all members of the crew. Work at remote locations will require use of cell phones or a means of positive communications.

8. The familiarity of each climber regarding the location AND operation of any rescue equipment and location of a first aid kit.

9. The tower should not be climbed in inclement weather, when electrical storm activity is forecast, or when fog obscures that portion of the tower to be climbed. In locations where fog is usually present and where unacceptable delays would result while waiting for the fog to dissipate, the tower may be climbed provided the climber and safety observer are equipped with reliable two-way radios. Radio checks should be initiated at least every 5 minutes.

10. The tower shall be de-energized for mounting, climbing and dismounting, except as noted in parts II.B.1 and II.B.2 of this

2-5 chapter. A deadman stick shall be used to positively ground the tower.

11. A safety lanyard shall be attached to all tools and equipment on the tower to prevent missile hazards.

12. Site Safety Meeting - Upon arrival at the site, all climbers shall hold a pre-climb safety meeting. Ensure every climber knows where emergency equipment is stored and where emergency medical facilities are located. The length of these meetings is directly related to the complexity and type of work to be performed.

a. Hazard Assessment: Review all possible hazards to include:

(1) Weather related, such as wind, snow, ice, moisture, lightning and sunshine.

(2) Electrical dangers.

(3) Noise.

(4) Live hazards such as snakes, birds, insects, rodents, farm animals and other humans.

(5) Other conditions, including non-standard structure hazards.

b. Perform individual pre-climb inspections to include route inspection.

G. Conditioning and Mechanics of Climbing.

1. Personal condition is as important as the safety equipment. For safety, you will need physical well-being, emotional conditioning, a well-rested mind and body, self-confidence and freedom from drugs of any type. Get plenty of sleep and eat sensibly. Keep your fluid intake adequate. Never consume alcohol prior to or while climbing.

2. Ascending/Descending

a. Climbing is a physical process and requires practice to do it correctly. CLIMB WITH YOUR LEGS, AND NOT YOUR ARMS. Climbing is not a race. Your goal is to arrive at your work location comfortable, relaxed and ready to work.

b. No one should stand around the base of a tower while a person is ascending or descending or working.

c. Use of a safety climb device requires that you keep three points of contact with the structure. Do not jump or hop.

(1) Climb with your legs, not your arms.

(2) On tapered towers climb on the high side or side that allows the climber to naturally lean into the tower.

(3) Legs lead on the climb, arms lead on the descent.

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(4) Rest often and use rest platforms when they are available.

(5) Keep body swing to a minimum.

(6) Be well rested, confident and drug-free.

d. Maneuvering- Climbing and maneuvering on communication towers uses body mechanics that predominately involves the use of the arms and legs. "Look before you leap". Before undertaking any physical maneuver, consider carefully what you are doing. When suspending or descending use approved descent equipment that is designed to control your descent mechanically, not physically.

If you are in doubt as to how to reach a particular location on the structure or how to perform the task in a location, consult other team members and your supervisor. Consider different physical actions and select the one that best suits your skill, strength, condition and experience.

e. Crossing and Positioning - Before exiting a safe climb device, you must determine the need for fall protection. You must be continually aware of the location of other climbers and their anchorage points. Pay particular attention to attaching to diagonal structures or members. Remember that the connector will slide down diagonal structures. During the cross to a work area you must maintain 100% fall protection, which generally means 100% connection to the structure. The 100% connection rule is as effective as your attitude. If you are tired or tense, stop and connect with your lanyard and rest. Climbers are exerting physical energy and can often become over fatigued. When you are tired, cold, hungry, cramped or distracted, you are not safe.

f. Working on a Structure - Select a proper structure and wrap your positioning lanyard around the structure so it allows movement of your hands sufficient for the task. A rule of thumb is hold your elbow at your waist and move your arm up and down from chin to lap. If you do not contact the structure, the distance is correct. Be sure that the lanyard is connected and properly locked. NEVER TRUST THE SOUND OF THE HOOK OR CONNECTOR.

Visually sight your hardware and ensure that it has closed and is locked. Do not attach safety lanyards to guard rails, hoists, platform gratings, lighting equipment or any loose equipment on the tower.

H. Rescue. There are five generally accepted rescue techniques. Each of the below techniques requires specific training and equipment. These techniques must be practiced on a recurring basis and as such are considered an integral part of any tower training conducted.

1. Manual rescue: Reaching a fallen worker from the structure and pulling him back to the safety of the structure.

2. Outside Services: Professional rescue services; These should be used when available and if the response time is adequate.

3. Winch Rescue: If a winch is available and rigged, or can be rigged, attach an injured worker to the winch line and lower the victim to

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4. Ascending/Descending Systems: These are manually operated devices that are appropriate to many climbing environments and to one-rescuer operation.

5. Approved suspension systems: This is an approved descent and suspension device that can be used to reach a fallen climber and assist the climber to the ground.

Credit: Much of the information contained in Part I of this Chapter was taken directly from Tower Climbing Safety and Rescue, Second Edition, published by ComTrain, 1999.

PART II. GENERAL TOWER SAFETY

A. Climbing of Towers by Contractor. Contractor personnel shall be bound by all applicable OSHA regulations whenever a tower is to be climbed and shall be familiar with the contents of this manual. In addition, whenever a tower is to be climbed the following conditions apply:

1. The tower should not be climbed in inclement weather, when electrical storm activity is forecast, or when fog obscures that portion of the tower to be climbed.

2. The tower shall be de-energized for mounting, climbing, and dismounting. Exceptions are noted in section B below.

B. Work on Energized Towers. Only LORAN-C towers may be climbed while energized. NDGPS and DGPS shall not be climbed under any circumstances while energized. All personnel working on or near energized Loran-C towers should be familiar with Sections II and III of Appendix E. All personnel working on energized Loran-C towers shall be qualified climbers. Mounting and dismounting energized towers, and performing maintenance outside the cross-section of energized towers should be the exception rather than the rule. Work required on an energized LORAN-C the tower can be accomplished with a minimum of RF exposure, if the personnel remain within the tower structure and below the base of the top platform.

When the work is required above the base of the platform, it is recommended that transmissions be secured as permissible exposure limit (PEL) is exceeded approximately one foot above the platform base. When work is to be accomplished within one foot of the feed point or feed wire run, the transmitter should be secured.

1. Mounting and Dismounting. Loran-C towers may be mounted and dismounted without de-energizing the tower provided the procedures detailed in Appendix E are strictly followed, and when conditions exist that do not permit the use of momentary off-air time. When work is required while a LORAN-C tower is transmitting, it is recommended that the tower access ladder be set in place by personnel other than the actual tower climber. Upon ladder placement, personnel should exit the area. The tower climber should then enter the PEL area, climb the ladder and enter the tower as described in Appendix E.

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2. Climbing Towers for Inspection, Painting, or Repair. Loran-C towers may be climbed while they are energized. When climbing energized Loran-C towers the following precautions should be taken:

a. The conditions of Part I.B or Part II.A of this chapter, as appropriate, shall be met.

b. Because of the inherent danger of RF exposure, climbers must remain inside the tower cross-section, extending hands and arms only as necessary to reach lighting fixtures or other accessible tower components, and extending the head only as necessary to take twist readings by the leg sight method (see Ch.8 G.2.a), or to visually inspect the outside faces of the tower. Exceptions to this precaution are detailed in Appendix E, and apply only to Loran-C towers not exceeding 1000 feet in height. For further information or clarification, see the Electronics Manual, COMDTINST M10550.25(series) or contact the CG Command and Control Engineering Center (C2CEN).

c. Climbers should avoid extending any part of the body beyond the corona shield/guard rail at the top of the tower.

C. Maintenance of Energized Towers. Maintenance of Loran-C towers that can be performed with the maintenance personnel inside the tower cross-section may be performed while the tower is energized provided the provisions of Part II.B above are complied with. Tower maintenance outside the tower cross-section and on the guy cables and insulators should be done during periods of off-air time. Requesting off-air time is an inherent part of scheduled recurring maintenance. It is the preferred method for performing maintenance. Maintenance efforts that require someone to be outside the tower cross-section may be performed on energized Loran-C towers provided the provisions of Appendix E are complied with and circumstances prevent the use of off-air time to perform the maintenance.

D. Ladders and Safety Climbing Devices. It is Coast Guard policy to conform to the Occupational Safety and Health Administration (OSHA) Standards with respect to ladders and fall protection. The following requirements reflect the latest interpretation and adaptation of these standards for Coast Guard towers:

1. All new towers shall be constructed with a fixed ladder equipped with a ladder safety climbing device. Rigid rail safety climbing systems which meet Federal Specification RR-S-001301 Type I are required. The Saf-T-Climb system, manufactured by North Safety Products (http://www.northsafety.com/) is the preferred rigid rail climbing system. Existing towers that do not have fixed ladders shall, if practical, have ladders with ladder safety climb devices installed under the AFC-43 maintenance program.

2. All towers shall have a reasonable and safe means of ascending and descending the structure. Loran-C, radar antenna support, and similar tall towers should be equipped with fixed metal ladders conforming to OSHA Standards 29CFR1910.27, "Fixed Ladders", Subpart D and 1926.1053,Ladders, Subpart X. Even though the use of ladders is not considered mandatory by OSHA, the use of ladders remains the most practical and safe means of climbing towers. Towers, monopoles, and

2-9 http://www.northsafety.com/ all elevated structures shall have a safety climb system installed to the extent it is possible and feasible. When the configuration of the structure will not allow installation of a ladder with safety climb system, alternative methods of providing fixed anchorage to ensure climbers' safety is required. When modification to a tower to include a heavy metal ladder is not structurally feasible or economically justified, the original design is acceptable provided a safety climbing system as described in D.1. above is installed.

3. Poles or similar non-lattice type structures which are not equipped with authorized safety climbing devices and/or an adequate ladder or climbing surface must be climbed only by contractor personnel or by specially trained Coast Guard personnel.

E. Protective Barriers and Warning Signs. To protect the towers and anchors from vehicular damage as well as to guard against injuries to personnel, the following protective barriers and warning markers shall be provided:

1. A permanent, single gated fence, constructed of non-conductive material shall be installed to completely enclose the immediate area around the base of each transmitting antenna tower. "High Voltage" warning signs should be conspicuously placed on the outside face of each side of the fence and on the gate. The gate should be padlocked at all times, except when authorized personnel are within the enclosure or are on the tower.

2. Where access roadways are located under low-hanging guys, warning signs that provide the clearance in feet and meters should be installed on the lowest guy. Where perimeter fencing for an entire antenna field or station is not provided, and where the public can gain unrestricted access to the guy anchors, consideration should be given to enclosing each anchor by a fence with a lockable gate.

Anchors not so enclosed should be marked in one of the following ways:

a. Prominently placed wooden posts painted in alternating yellow and black stripes to alert pedestrian and vehicular traffic. The posts should be nominal 4"x4" in section, and should extend at least 4 feet (1.2m) above ground level. The placement and number of posts should be such that traffic is directed around the anchors and away from the guys.

b. If the anchor concrete or steel is prominent and not liable to be covered with vegetation, these anchor components may be painted in alternating yellow and black stripes to alert traffic.

c. Retroreflective, brightly colored reflective guy guards, such as those manufactured by the Preformed Line Products Co., may be installed on the lower portion of the guys.

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CHAPTER 3. INSPECTION GUIDELINES

A. General. Sources of technical and historical information on each tower and guidelines and responsibilities for inspection and maintenance are covered in this chapter.

1. Tower Manuals and Drawings. An erection manual, erection and fabrication drawings, and, in some cases, maintenance manuals are furnished with each tower. These materials are the only source of specific data on the various components of each tower, and they should always be readily available to personnel charged with tower inspection and maintenance responsibilities. As tower modifications are made, the drawings and manuals should be annotated with the date and description of the modifications. The information contained in this Manual does not duplicate the information contained in the tower manuals and drawings furnished with each tower. Operational and support commanders shall forward to the servicing Civil Engineering Unit (CEU) and the Tall Tower Coordination Center updated drawings whenever towers or antenna systems are modified.

2. Inspection and Maintenance Records. The servicing CEU should maintain a complete file for each tower or antenna system containing:

a. Inspection reports.

b. Specifications used for inspection or maintenance.

c. Correspondence pertaining to the particular tower or antenna.

d. Records of all maintenance or modifications.

e. Updated inventory of tower spare parts.

f. Pertinent procurement documents.

B. Inspection Categories.

1. Tall Tower Coordination Center (TTCC) Level. This category of responsibility includes policy development, technical assistance to support CEUs, MLCs and other units involved with the tower program.

Periodic tower inspections may also be conducted by TTCC personnel.

Except in an emergency, the TTCC should also be invited to review proposals for repair, modification, or replacement of major tall tower system components. "Major components" are tower guys, anchors, legs, horizontals, diagonals, foundations, and insulators.

2. Major Field Command Level. This is the primary level of responsibility and rests with the CEU. Responsibilities at this level include:

a. The administration and planning for all inspection and maintenance activities.

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b. Providing technical assistance, contract services, materials, and equipment as may be required to perform inspection and maintenance activities.

c. Determination of inspection frequency as well as training and designation of inspectors.

d. Determining which inspection and parts maintenance items are to be performed by station and field personnel; and training the station and field personnel to accomplish these tasks.

e. Determining major maintenance requirements, and seeking approval for repair, modification, and/or replacement of major tower system components (see B.1 above).

3. Intermediate Level. This intermediate level of responsibility, if established, will consist of such responsibilities outlined in B.2 above as may be delegated by the CEU. Typically ESUs, Groups and some elements of MLC staff fall into this category depending on the tower function.

4. Unit/Field Level. Through years of experience, it has been determined that unit and field personnel must play a very important role in the inspection and maintenance program. A large number of Coast Guard units with towers are located in remote areas, and the attentive and properly trained eyes of field personnel are therefore essential tools of the servicing CEU. In addition to certain routine inspection responsibilities such as noted in C.3.a below, the field unit or station shall conduct a visual check of tower alignment (see Ch.8 G.) and the general tower condition (from the ground) following each heavy storm, earthquake, or icing condition (see Fig.

3-1).

C. Inspection Objectives and Requirements. Inspection on a periodic basis is the most effective way to protect the Coast Guard's investment in towers. Major field commanders should consider it their first priority, where the antenna system is concerned, to establish a sound inspection program utilizing all of the expertise available. In this way it will be possible to provide for the timely detection and correction of deficiencies before major tower maintenance or repair become necessary.

With early detection and correction, both costs and off-air time will be minimized.

1. Inspection Frequency and Effort. Because of seasonal storm cycles, antenna systems should be carefully inspected about once per year, making allowances for local conditions, expenses involved, expertise availability, and the magnitude of the original capital investment.

The quality of an inspection is only as good as the personnel performing the inspection. Almost complete reliance is placed on visual inspection methods. The ability of the inspector to detect potentially hazardous conditions and to recognize serious defects is of paramount importance. A hurried or superficial inspection cannot produce the desired result, regardless of the ability of the inspector. Inspectors should be guided by detailed information contained in this Manual.

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Figure 3-1 625 ft Tower deflected due to heavy icing conditions.

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2. Contract Inspections. Because contracting for inspection services is usually expensive, efforts should be made to maintain an in-house inspection capability. However, there are several major tower inspection, manufacturing and erection firms providing these services. In either case, it should be recognized that the capabilities of the personnel offered by these firms can vary considerably, and the inspection results will follow suit. Whenever doubt exists as to individual capabilities, a thorough investigation should precede selection of a particular contractor. CEUs should develop lists of qualified firms.

a. Scope and Scheduling. To gain maximum benefits from contract inspections, the scope of the inspection work should be clearly and concisely defined and the inspection period should take full consideration of weather conditions. Inspection items that cannot be satisfactorily performed by Coast Guard personnel should be included in the scope of work of inspection contracts.

b. Analysis and Evaluation. A Coast Guard representative should be assigned to accompany the contract inspector. The representative should have a technical background such that he may make reasonable independent evaluations of the contractor's inspection technique and recommendations. In every case, the findings and recommendations of a contract inspector should be thoroughly reviewed and analyzed in order to preclude unconditional acceptance of his work. It may be necessary to inspect again or to test components before a course of action should be planned.

3. Coast Guard Inspections. Most tower inspections can be adequately performed by Coast Guard personnel familiar with general maintenance requirements and practices. By accepting a substantial portion of the inspection burden, the Coast Guard will produce a more effective and less costly inspection and maintenance program. In-house expertise is the best kind. All CEUs should concentrate on building this expertise through training programs and the experience of their staff personnel. Expertise known to be available in the staffs of various field commands should be utilized by other commanders to the maximum extent mutually acceptable.

a. Inspection by Station Personnel. Considering their full time availability, station personnel should be used to the maximum possible extent for ground level tower inspections. Station personnel should not be required to perform routine inspections on towers; however, they should not be prohibited from climbing towers for non-routine maintenance (see Ch.4 A.3). During visits to units, Coast Guard civil engineers and tower specialists should take time to tour the tower site with the station commanding officer and selected crew members in order to point out and explain the various items to be checked in a unit inspection. Such items include but are not limited to:

(1) Corrosion at particularly susceptible locations, including guy pull-offs, bonding straps, leg flanges, anchor arms and any tower metal in contact with soil or water.

(2) *Damaged or missing cotter pins.

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(3) *Slipped or unraveled guy-grip dead ends. (See Ch. 6 H.3)

(4) *Crossed guys in a face-guyed tower.

(5) *Chipped, cocked, or missing insulators.

(6) Operation of the lighting system. (See Ch. 9 E.)

(7) *Missing or inadequate safety wire on turnbuckles. (Ch. 6

I.2.)

(8) Cracked or shifted concrete.

(9) *Evidence of arcing on the guys or at the tower base.

(10) *Position of lightning ball gaps (Ch. 9 F).

(11) Damage to the ground radial system or grounding straps.

(12) *Damage to or oil loss from the base insulator.

(13) *Failed fiberglass rod insulators. (Ch. 6 J.2)

(14) Safety requirements. (See Chapter 2)

* - Guyed towers only

b. Inspection by Other Field Personnel. The majority of Coast Guard towers are located in remote or unmanned locations and are visited by contractors and technicians from intermediate level units. CEUs should take advantage of these scheduled visits for inspection of these unmanned tower sites. The intermediate level personnel should be trained by CEUs to check basic inspection items outlined in a.(1)-(14) above.

c. Inspection Routine for Manned Tower Sites. The following general inspection routine is recommended for station personnel at manned tower sites. CEUs should provide unit level commanding officers with a more detailed routine, based on local considerations.

(1) DAILY - Visually check the lights after sunset unless monitored by an automatic failure alarm system.

(2) WEEKLY - Visually check all guy assemblies and tower structural members from two or more good vantage points on the ground. For energized towers, check for visible or audible corona or arcing on any antenna system components.

(3) MONTHLY - Visually check each anchor and the tower for abnormal conditions (see C.3.a above). Visually check tower alignment in accordance with Ch.8 G.1.a.

(4) ANNUAL - CEU and or contracted tower inspection for tall towers.

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(5) TRIENNIAL - CEU and or contracted tower inspection for small

d. Inspection Routine for Unmanned Tower Sites. The following general inspection routine is recommended for unmanned tower sites. CEUs should provide field and support commands with a more detailed routine, based on local considerations. CEUs and other support commands should work closely to ensure unmanned sites receive proper preventative maintenance and inspection.

(1) Preventative Maintenance Visits - Coast Guard personnel visiting unmanned sites for routine preventative maintenance should conduct the following using the small tower report (format 1) in Appendix B as a guideline. Visually check the lights in all modes of operation. Visually check all guy assembly (where present) and all tower structural members from two or more vantage points on the ground. For energized towers, check for visible or audible corona or arcing on any antenna system components. Visually check each anchor and the tower for abnormal conditions. (see C.3.a above). Visually check tower alignment in accordance with Ch.8 G.1.a.

(2) ANNUAL - CEU and or contracted tower inspection for tall

(3) TRIENNIAL - CEU and or contracted tower inspection for small

e. Inspection by Coast Guard Civil Engineer or Coast Guard Staff

Tower Engineer. The CEU Commanding Officer should ensure that one or more members of the CEU staff is fully qualified to perform tower inspections, including climbing of energized towers where necessary and authorized (Ch.2 Part II.B.1). Selected station personnel should accompany the inspector during the entire inspection, to assist and to learn. In addition to the items listed in C.3.a above, inspections by these staff members should include the following:

(1) Measurement of alignment and twist.

(2) Measurement of guy tension where feasible.

(3) Inspection of the lighting system, and relamping.

(4) On-tower inspection for corrosion, paint condition, damaged members, loose bolts, missing or damaged hardware, ladder and safety rail condition, etc.

4. Inspection Reports. A simple procedure for reporting station level inspections should be established by the servicing CEU, whereby only exceptions to the norm are reported (see format 1 of Appendix B).

However, reports of inspections by Coast Guard civil engineers, tower specialists, and contractors should be as detailed as possible; they should contain, as appropriate, plots of alignment and twist, guy tension readings, accurate descriptions of discrepancies and their location, and good color photographs (see format 2 of Appendix B).

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Simplicity, brevity, and substance should be the attributes of the narrative portions of inspection reports. Maximum use should be made of color photographs to show normal, typical, and unusual conditions.

Copies of reports showing unusual conditions or procedures should be forwarded to other field commands that are responsible for similar

D. Tower Failures.

1. Past Failures and Causes. Major tower failures have occurred over the years, providing a number of "lessons learned" which are reflected by certain sections of this Manual and in current procurement specifications. These failures and their causes are:

a. LORSTA Carolina Beach - 1961 - A self-supporting 625-ft tower buckled at 2/3 its height in a storm. Top-loaded radials had been added to a tower originally designed for no radials, and their presence overloaded the tower.

b. LORSTA Ejde - 1962 - A structural guy slipped through cable clips securing the guy at the anchor end, resulting in the collapse of a 625-ft tower.

c. LORSTA Iwo Jima - 1964 - A threaded eyebolt in a TLE insulator failed, causing swing-in damage to tower members. During the subsequent repair operation, the 1350-ft tower collapsed with workmen aboard. The apparent cause of failure was the lack of proper temporary bracing.

d. LORSTA Yap - 1964 - An error in procedure during erection caused the collapse of a partially erected 1000-ft tower.

e. LORSTA Angissoq - 1964 – Fatigue failure of the eyebolt head in a compression cone insulator on a structural guy caused the collapse of the 1350-ft tower.

f. LORSTA Jan Mayen - 1980 - Improperly installed tensions in combination with a heavy ice loading apparently caused this 625-ft Stainless Model 1300 tower to collapse.

g. COMMSTA Miami – 1992 – Two 300-ft guyed…