NOAA Standard Specification MOC-635-1 Thermal Insulation for Piping.pdf

MOC-635-1

OCTOBER 1989

NATIONAL OCEANIC AND ATMOSPHERIC ADMINSTRATION (NOAA)

MARINE OPERATIONS CENTER

STANDARD SPECIFICATION MOC-635-1

THERMAL INSULATION FOR PIPING

1. SCOPE. This specification contains the general requirements for renewing and installing thermal insulation on piping and tubing of NOAA ships.

2. REFERENCES.

a. NOAA Standard Specification MOC-000-1 (latest revision), “General Requirements for Ship Repair Contract Work on NOAA Ships”

3. REQUIREMENTS.

3.1 General. The following requirements apply to all insulation renewal and repairs, regardless of the type of insulation of surface temperatures involved.

3.1.1 Whenever removal or renewal of existing insulation is

necessary to accomplish the required work, the contractor shall remove and properly dispose of all existing insulation. If the existing insulation contains asbestos materials, comply with Section 4.11.7 of reference 2.a. All suspect materials shall be considered to contain asbestos unless proven to be otherwise.

The contractor may have samples analyzed by a qualified laboratory to prove or disprove the presence of asbestos.

3.1.2 Except as otherwise specified, the following piping having external temperatures higher than 125 degrees Fahrenheit shall not be insulated:

a. Any hot surface for which freedom from insulation is essential for its proper operation.

b. Relief valves, and piping beyond the valve discharge, except as required for personnel protection.

c. Pressure gauge piping.

d. Piping in bilges, voids, and cofferdams.

e. Piping over shower stalls, and behind and under lavatories.

3.1.3 Insulation on new piping shall not be installed over

mechanical, welded, or brazed joints until all required tests and inspections have been completed and accepted.

3.1.4 Sectional preformed thermal insulation shall be applied with end joints broken by starting with a whole-length piece and a half-length piece.

3.1.5 As used in this specification, “piping” includes all pipe, tubing, elbows, tees, valves, unions, couplings, expansion joints, flanges, and other pipe fittings in the specified length of pipe.

3.2 Hot Piping. The following requirements apply when applying thermal insulation to piping where the contact temperature exceeds 125 degrees Fahrenheit:

3.2.1 Materials.

a. Preformed sectional thermal insulation pipe covering complying with MIL-I-2781 shall be used for piping where the contact temperature exceeds 350 degrees Fahrenheit.

b. Fibrous glass preformed sectional thermal insulation pipe covering complying with MIL-I-22344 shall be used for piping where contact temperature is between 125 and 350 degrees Fahrenheit.

c. High temperature insulating cement shall comply with

MIL-C-2861.

d. Finishing cement shall comply with ASTM C449.

e. Fibrous glass cloth, tape and thread shall comply with MIL-C-20079. Lagging cloth shall be Type I, Class 3, with red coloring.

f. Fibrous glass wire-reinforced cloth and tape lagging material shall conform to HH-P-31, Type I, Class 1.

g. Adhesive cement shall comply with MIL-A-3316.

h. Fire-retardant paint shall comply with DOD-E-24607.

3.2.2 Installation.

a. Apply preformed sectional pipe covering directly to the piping. Whenever possible, use double-layer construction for pipe that has surfaces above 600 degrees Fahrenheit. When single-layer construction must be surfaces above 600 degrees, provisions shall be made to permit thermal movement of the piping without the opening of insulation joints.

b. When a single layer of insulation is installed, butt-joints of the two halves of the sectional insulation shall be staggered. Where double-layer construction is used, layers shall be placed in such a manner as the stagger both butt and lateral joints. Each segment shall be securely fastened in place.

c. Where bends or elbows are encountered, sectional preformed insulation shall be cut or mitered to provide a smooth fit around the contour of the bend.

d. When new insulation is installed to a greater thickness than adjacent existing insulation, the transition joint between the existing and the new shall be tapered over at least 3 inches with high temperature cement.

e. On pipes insulated with calcium silicate preformed sectional pipe covering, insulation shall be applied at pipe hangers by cutting and fitting the covering around the pipe clamp and hanger. Fill the voids and cracks with high temperature insulating cement.

f. On pipes insulated with fibrous glass preformed sectional insulation, insulation shall be stopped where pipe hangers are clamped to the pipe. Fill the remaining space with layers of glass felt to the thickness of the adjoining pipe covering and fill voids and cracks with high temperature insulating cement. Smooth the surface with finishing cement and apply fibrous glass cloth and adhesive.

g. All openings, voids, and cracks in the insulation shall be filled with high temperature insulating cement.

h. Where insulation terminates at flanges, provisions shall be made for removal of flange bolts or bolt studs without removing sections of insulation on adjoining piping by stopping off the insulation squarely at a distance 1/4-inch greater than the length of the flange bolts or bolt studs.

i. Expansion joints, valves and flanges shall be insulated with removable flexible covers as follows:

1. Covers shall be the same thickness as the preformed sectional pipe covering.

2. The covers shall be fabricated so that they overlap the adjoining pipe insulation a minimum of 2 inches. The covers shall be manufactured using insulation felt covered with 0.008-inch diameter knitted wire mesh sewn on glass cloth, or wire-reinforced glass cloth, conforming to HH-P-31, Type I, Class 1, on the inside (hot side) and end surfaces, and glass cloth conforming to MIL-C-20079, Type I, Class 9, on the outside. Each half section shall be sewn and, where required to prevent sagging, quilted with fibrous glass thread or wire-reinforced glass thread, as applicable. As an alternative, the covers may be fastened mechanically with stainless steel staples in a manner that will provide uniform thickness, strength and rigidity.

3. When the outside diameter of the fitting or flange is greater than that of the adjacent pipe covering, glass felt shall bed used to build up the outer edges of the reusable cover to the required diameter.

4. When installing the covers, fill the spaces between the removable cover and the surfaces they protect with pieces of insulation felt. The felt shall be packed loosely enough to preserve air cell structure, but tightly enough to prevent air circulation.

5. Covers shall be secured by lacing stainless steel wire through hook or ring fasteners.

6. Covers over expansion joints and fittings shall be installed in a manner that movement due to thermal expansion is not restricted.

j. In lieu of removable covers, valves and fittings may be insulated by cutting insulation felt into suitable widths and building up the thickness to within 1/2-inch of the adjacent pipe covering. Spaces that cannot be filled with layered felt shall be filled with loose felt. The felt shall be secured in place with wire and overlaid with 1-inch square wire mesh. A 1/2-inch thick coating of finishing cement shall be applied, troweled to a smooth finish, and then lagged with glass cloth.

Flanges shall be insulated with removable covers.

k. Insulation support rings shall be installed at the vertical rise of all exhaust piping before installing insulation.

l. Each layer of sectional pipe covering shall be secured with 18-gauge stainless steel or monel wire or with stainless steel flat bands. Not less than three loops or bands shall be used for fastening each three-foot section of insulation on pipe up to 6 inches outside diameter. Use four loops or bands for fastening each three-foot section of insulation on larger piping. The ends of the wire loops shall be fastened together to hold the insulating material tightly against the pipe. The wire ends shall be bent over and carefully pressed into the pipe covering to leave no projection.

m. Smooth the outer surface of the insulation using finishing cement troweled to a uniform finish. Cover the insulation with fibrous glass lagging cloth, secured to the insulation with adhesive cement and tightly fitted with all joints lapped by a minimum of 2 inches to present a smooth appearance. Coat all cloth lagging with one coat of adhesive cement for sizing.

n. After the adhesive cement has dried, apply one coat of fire-retardant paint to all lagging.

o. Thickness of insulation complying with MIL-I-2781 shall be in accordance with the following table.

Nominal Pipe Size (inches)

Max Operating Temp. (degrees F)

Insulation Thickness (inches)

Less than 3 Less than 750 751 to 900

Greater than 900

2-1/2

3 through 7 Less than 350 350 to 750 751 to 900 901 to 950

Greater than 950

2-1/2 3-1/2

4-1/2 5-1/2

Greater than 7 Less than 350 350 to 750 751 to 950

Greater than 950

2-1/2

p. Thickness of fibrous glass insulation complying with MIL-I-22344 shall be in accordance with the following:

1. For maximum operating temperatures up to 250 degrees Fahrenheit, insulation thickness shall be 1/2-inch.

2. For maximum operating temperatures between 251 and 300 degrees Fahrenheit, insulation thickness shall be 3/4-inch.

3. For maximum operating temperatures between 301 and 350 degrees Fahrenheit, insulation thickness shall be 1 inch.

3.3 Piping below 125 Degrees Fahrenheit. The following

requirements apply when applying thermal insulation to piping where the contact temperature is below 125 degrees Fahrenheit:

3.3.1 Materials.

a. Elastomeric tubular plastic foam performed sectional pipe covering complying with MIL-P-15280 shall bed used to insulate all piping.

b. Adhesive shall comply with MIL-A-24179.

3.3.2 Installation.

a. Install preformed sectional pipe covering to all piping and tubing and seal all edges with adhesive. To ensure a complete seal, fully cover all seams and butt-joints with adhesive. The surface nearest the pipe shall be pressed together first and evenly before joining the entire surface. Do not use tape in lieu of adhesive and do not stretch insulation to force longer length.

b. Where piping passes through joiner bulkheads or hull structure, insulation shall be installed intact where there is sufficient clearance. Where there is insufficient clearance, fit the insulation against the bulkhead or structure and seal the joint with adhesive.

c. Insulate valve bodies, flanges, and bonnets with carefully mitered and fitted pieces of the insulation. Seal all joints and bond using adhesive.

d. Insulate fittings and flanges with preformed pipe covering sized to match adjacent straight run piping insulation.

A step-type junction with the straight run piping shall be provided when the outside diameter of the fitting or flange is smaller than the adjacent straight run piping insulation. Where the fitting or flange outside diameter is larger than the adjacent pipe covering, circumferential spacers of elastomeric foam plastic shall be used to build-up the required diameter.

Void areas shall be filled with pieces of foam plastic.

e. When rubber block hangers are used, the insulation shall butt against the rubber stock. Joints between the rubber block hanger and pipe insulation shall be sealed with adhesive. When rubber-lined pipe hanger assemblies are used, the insulation shall be run up to, and fitted carefully around, the clamp and hanger rod/support strap. A layer of elastomeric foamed plastic shall be bonded around the pipe hanger, overlapping the pipe insulation and clamp. All joints where hanger clamps and support straps penetrate the insulation are to be sealed with adhesive.

f. When a refrigerant pipe passes through an insulated bulkhead into a refrigerated space, the piping cover shall extend into the room at least 1 inch beyond the bulkhead.

g. One-hundred percent bonding of all joints is required in order to ensure a continuous vapor barrier throughout the length of piping and at valves and fittings. Condensation of water vapor to the joints, valves, fittings or hangers will constitute evidence of improper installation and must be repaired by the contractor.

h. After completing installation of the elastomeric foamed plastic pipe covering and sealing all joints, apply one coat of Devoe and Raynolds DEVFLEX 1 to ensure that the seams will remain tight. Apply one coat (1.0 to 2.0 mils dry film thickness) of Ocean Chemical Company “Ocean 634” and two coats (5.0 mils dry film thickness per coat) of “Ocean 9788”. All coatings shall be in accordance with the manufacturer’s printed recommendations.

i. Thickness of the insulation shall be as follows:

Temperature (Degrees

Fahrenheit)

Thickness (inches) Air-conditioned spaces

Thickness (inches) Non air-conditioned

Spaces Less than 0 1 1-1/2 0 to 40 3/4 1 41 to 99 1/2 3/4