NOAA Standard Specification S4800-2 Piping Systems.pdf

July, 1984 (7/96)

NOAA STANDARD SPECIFICATION S4800-2

PIPING SYSTEMS - GENERAL REQUIREMENTS

1. GENERAL

The intent of this Section of the Specification is to set forth the general requirements for all machinery piping systems with respect to system design, installation, restrictions, corrosion precautions, valves and fittings, and cleaning and flushing. For details or specific requirements of a particular system, refer to the Section which describes the system.

Materials of pipes, valves and fittings shall be as indicated in Table 74 at the end of this Section. Where valves are indicated to be galvanized, they may be treated with the electroless nickel plating process in lieu of galvanizing.

All valves, flanges and fittings shall be supplied by manufacturers listed in USGS COMDTINST M16714.3 (old CG-190), or a USCG approval affidavit shall be furnished to the Owner.

All piping passing overhead in the Galley and dining area shall be type "K" copper or Schedule 80 IPS as appropriate.

2. SYSTEM DESIGN

System piping and associated components shall be designed to provide adequate flow to all equipment served. The use of automatic regulators and/or restrictive devices, such as orifices, in lines servicing auxiliary components, such as heat exchangers, are permissible for obtaining and maintaining operational conditions, providing they do not impose undue restrictions, such as large pressure drops (necessitating and increase in pumping power) or destructive erosion conditions.

Orifices, where required, shall be incorporated at flanged joints. The design of orifice plates shall be such that a portion of each protrudes visibly beyond the incorporating flanged joint. Orifice size shall be stamped on the "pan handle".

All automatic control valves shall be designed and installed to meet full operational requirements, permit field adjustments, inspection and maintenance without removal from the line. They shall also be designed to assume a fail-safe position which will satisfy the requirements of system safety while affording continued operation.

A self-cleaning "Y" or basket type strainer shall be incorporated upstream or each automatic control valve.

In order to meet operational requirements and to facilitate on board and depot maintenance, bypass, isolation and/or stop valves shall be incorporated for the control of individual and/or sectional systems, to include all branch lines and mains (headers. Maximum isolation capability is desired so that individual components may be secured while the vessel is in service without the disruption of similar items.

Check valves shall be incorporated wherever flow reversals would be detrimental to operational requirements. Stopcheck valves shall be incorporated wherever flow reversals could flood a space.

Manually operated valves shall be readily operable by one person, directly or through mechanical advantage type operators. The valve control handles shall be easily accessible to operating personnel without the need for lifting or reaching below floor plates or gratings. Solid reach rods shall be provided as necessary to avoid such lifting or reaching.

Where solid reach rods cannot be installed, reach rods of a flexible type shall be used. All valves, 2½" and over, shall be labeled or stamped on the valve control handle to clearly show the direction of movement required to open and to close.

Where the penetration of a watertight bulkhead or deck is required, the piping shall have an approved penetration fitting installed, to insure that watertight integrity is maintained. In no case shall the bulkhead or deck plate be used to form part of a joint or piping system.

Wherever PVC piping penetrates a fire boundary, the PVC pipe shall not penetrate the division, but must be connected to a steel spoolpiece with an acceptable metallic shutoff valve installed at the bulkhead or deck.

Spoolpieces and valves are not shown on the drawings as final routing of piping is the responsibility of the Contractor.

To prevent damage to piping and joints at bulkheads and decks, provide bends or fittings for expansion of piping and for movement due to the working of the vessel's structure. Piping to reciprocating machines shall have flexible connections, located as close to the machines as is practicable.

All compressed air system flexible connections shall be stainless steel "hose" (fine corrugation bellows), with braided stainless steel covers.

Hosing shall be sized to 1½ times the working pressure of the system and be suitable for temperature ranges of system operation. In low pressure systems, hose and connections shall be IPS, threaded, flanged or clamped. All fuel oil connections shall be SAE straight thread, with "O" ring seals. All flexible connections shall be "Anchor", "Aeroquip", or equal, with wire inserted hose covered with a fire sleeve in accordance with CFR46.

Flexible connections or take down joints of rubber or neoprene hose with hose clamps ("PEDROS") are not permitted without prior written approval by the Owner.

Piping shall be sized as indicated on the drawings. Fluid velocity criteria given in the following table shall be used in sizing any additional piping requirements not covered in the Specification or on the Contract Plans and Contract Guidance Drawings. Size selection shall be refined to suit particular requirements, such as pump suctions, to avoid cavitation, erosion, water hammer and noise.

FLUID DESIGN VELOCITIES

Fluid Velocity, fps

SERVICE NOMINAL MAXIMUM

Fuel Oil Suction 2 D 7 Fuel Oil Discharge 5 D 12 Lube Oil Suction D 4 Lube Oil Discharge 2 D 6 Steam 50 D 150 Condensate Drains 0.3 D 1 Sea Water Suction 3 D (b) Sea Water Discharge 5 D (b) Cold Fresh Water Suction 3 D 15 Cold Fresh Water Discharge 5 D 20

NOTES: (a) D is the pipe internal diameter in inches.

(b) 9 fps for galvanized steel pipe, except for services with occasional use.

3. INSTALLATION

Piping installation shall permit: free passage along walkways and ladderways; free access to perform shipboard operational and routine maintenance; free access to all doors, hatches and openings; and, as much as is practicable, be free of interference to the ready removal or the vessel's equipment and of system components for inspection, servicing, repair or replacement.

Suitable takedown joints shall be provided in piping to allow access to and removal of piping system components such as pumps valves and strainers and to remove unavoidable piping interferences to the ready removal of the vessel's equipment and of system components.

All pumps shall be provided with suitable takedown fittings to allow easy removal for servicing.

All piping shall be adequately supported by hangers, suitable for the material and service in accordance with Sketch AAASTD-074-SK05. Care shall be taken to assure that piping and hangers are of compatible material, where dissimilar materials occur, hangers shall be lined with approved isolation material. All valves shall be individually supported from the vessel's structure. Hangers shall be placed so as to avoid strain, where piping is connected to machinery. All non-ferrous piping which passes through a fire boundary shall be supported so that in the event of solder or brazing material melting, the piping system cannot sag or shift and thereby open a joint which would allow passage of smoke or flame.

Ferrous pipe and fittings required to be galvanized shall be galvanized by the hot dip process after fabrication where welding has been performed.

Where galvanized screwed fittings are required, both galvanized pipe and fittings are to be used. Where galvanizing is damaged during installation, a brush-on galvanized coating such as "Galvacon", or equal, shall be applied.

When reducers are required at pump inlets, provide eccentric reducers in a horizontal plane with the straight side on top to prevent air binding of the pump.

Connections shall be provided for thermometers (with dry wells) and pressure gages as required to check proper operation of systems and equipment.

To accomplish change in a direction, machine bending of pipe to a radius of five times the nominal pipe diameter for pipe 2" IPS and below, in lieu of elbows, is preferred. Copper tubing may be bent to a radius of three times the nominal diameter. However, in no case will machine bending of copper-nickel piping be allowed.

Unions are not permitted in piping behind linings, false ceilings or in other inaccessible locations.

To facilitate inspection and maintenance of equipment (including tube or tube bundle withdrawal on components having removable heads), the piping connecting thereto shall be arranged to permit access without breaking more than the connecting flanges.

Systems having unavoidable low points and/or pockets which may be effected by freezing temperatures or where trapped water may be detrimental to the operation of the system or system component shall be fitted with either flanged or bossed drainage fittings. Drainage points requiring drainage during start-up and those requiring relatively frequent manual drainage in service shall be provided with valved drains. Other points requiring drainage infrequently, in conjunction with maintenance, drydocking or periodic inspection may be provided with screwed plugs.

Where screwed plugs are incorporated they shall not be covered by insulation or linings, and shall be bronze for either ferrous or non-ferrous materials except that plugs exposed to sea water shall be monel.

Pressure control stations (reducing or regulating), unless specifically approved otherwise, shall consist, in the following order, of an isolation valve, self-cleaning strainer with valved blow-off (except in oil service piping), automatic control valve, isolation valve, pressure gage, and relief valve (where necessary). Pressure gages shall be provided with root valves as a means for isolation. A single valved bypass line shall be incorporated, connecting upstream of the upstream isolation valve and downstream between the downstream isolation valve and pressure gage.

4. RESTRICTIONS

No new piping shall pass through predominantly electrically equipped spaces, unless directly associated with and/or servicing such spaces.

Such piping shall be of one length throughout unless installation dictates otherwise. Necessary joints shall be either welded or brazed sleeved joints or otherwise shielded as approved by the Owner. At no time will piping be allowed above electrical switchboards or panels.

Existing threaded piping, in such spaces, shall have the joints of fittings seal welded.

Piping conveying flammable materials shall be routed to avoid being located within 18" of surfaces whose temperature is greater than 450°F under any condition of operation.

Piping penetration decks or bulkheads shall be fitted with minimum Schedule 80 pipe sleeves at all locations. Pipes shall pass through the sleeves which shall be continuously welded on both sides of the plating. Pipes shall be continuously welded to the sleeve.

Where a steel flange joins a cast iron flange, the steel flange shall have a flat face, and a full face gasket shall be used. All gaskets shall be compatible with the system served.

All globe valves shall be incorporated with the system's pressure under the disc.

Swing-check valves shall be incorporated, where possible, in a horizontal plane.

Except where otherwise specified, the designation of valve trim includes the following: stem, disc (or gate), nut, seat, back seating bushing and guides.

Assembled valves and fittings, in lieu of manifolds, shall not be acceptable except where closely positioned valves are of greatly varied sizes.

Use of mitered joints or mitered fittings shall not be permitted.

The use of cocks in place of valves is not permitted.

Drains from piping and equipment shall not be less than ½" IPS.

Silver-base filler metals used in the brazing of ferrous and nonferrous base metals shall conform to "Handy & Harmon", "Easy Flo", or equal.

For the brazing of 90-10 copper nickel pipe to valves and fittings, "Easy Flo", or equal, silver-brazing alloy shall be used. The brazing temperature should not exceed the annealing temperature of the base pipe material, but in no case should the brazing temperature exceed 1300°F for 90-10 copper nickel pipe.

5. CORROSION PRECAUTIONS

Piping conveying corrosive media shall be protected from the effects of corrosion and/or corrosion-erosion by the adoption of the following:

(a) Valves and fittings (except resilient-seated butterfly valves and other approved lined or liner type valves and fittings) in nonferrous piping runs shall either be bronze or material comparable to the applicable piping material.

(b) Where joints of ferrous and nonferrous materials cannot be avoided, a short "waster piece" at least 14" long of extra-heavy steel pipe shall be provided between the dissimilar metal lines. However, no "waster piece" is required where a nonferrous line connects to a ferrous line having a diameter two or more times larger. Waster pieces shall be designed for easy replacement and incorporated in readily accessible locations.

(c) Turbulence or flow(s) shall be minimized to curb corrosion/ erosion by restricting the velocities within the specified limits; by elimination of abrupt changes of pipe diameters in piping runs and connections; through the incorporation of gradual transitions in diametral changes; and by the use of long-radius bends and fittings, sweep tees, and "Y" and lateral type fittings. To assure smooth flow within the pipe, the following should be avoided: misaligned flanges; pipes not finishing flush with the flange face; protruding jointing material, weld or braze bead on the inside of the pipe;

and in general, sharp changes of direction and pipe sections.

(d) Body passages in throttling devices shall be designed to provide gradual changes in flow direction. In addition, the downstream cavity shall be as large as practical to permit dissipation of the issuing jet before making wall contact. At points where direct impingement at close range does occur, and cannot be avoided, section thickness shall be increased to provide adequate material to withstand the additional erosive effect. All piping downstream of throttling devices shall have a straight run at least 10 times the pipe's inside diameter.

6. VALVES AND FITTINGS

In general, use gate valves where shut off only is required; and globe or angle valves, installed with line pressure under the disc, where throttling is needed.

Valves shall be right hand closing when facing the end of valve stem and shall have either a rising stem or an indicator to show whether the valve is open or closed. Valves 2½" or over, except for butterfly valves, shall be commercially flanged with bolted bonnets and stuffing boxes.

Valves 2" and under shall have union bonnets, except as provided for in the Schedule.

Butterfly valves shall have resilient seats AISI 316 and stainless steel stems.

In general, provide flanged takedown joints in piping 2½" and over, and unions in piping 2" and under. Specific requirements are detailed on Table 74.

Takedown joints in soft copper tubing shall be SAE 45° flare type, with long nuts.

7. CLEANING AND FLUSHING

All piping, piping appurtenances, and applicable equipment shall be thoroughly cleaned after fabrication and prior to shipboard installation.

Internal surfaces of newly fabricated fuel oil, lube oil, and hydraulic fluid piping shall be cleaned by acid pickling or other suitable means to remove scale and contaminates prior to final assembly.

After complete shipboard installation each system shall be thoroughly cleaned, flushed of all foreign matter with the applicable system's medium, or an approved substitute, and tested in accordance with the Code of Federal Regulations (CFR), Title 46, Chapter I, Subchapter F, Section 56.97-40, Installation Tests.

System flushing shall be conducted at the applicable system's maximum operating pressure and temperature, and above normal line velocity.

Line vibrators, of the temporary in-line and/or portable hand types, shall be employed in all applicable systems, particularly the lube oil servicing systems. However, prior to flushing operations, such units as auxiliaries, heat exchangers, and control valves, having in-line mechanisms capable of trapping, or being affected by the carry-over, of foreign matter, shall either be removed or blanked off and bypassed.