Method Statement for Installation of Thermal Insulation on Pipes

Below is a detailed method statement for thermal insulation application on pipes, fittings and equipment connections.

Calcium silicate insulation is used for thermal insulation of indoor piping and fittings.

Perlite insulation is often used where water entering an insulation system may cause corrosion problems or process problems, for example the outdoor piping, fitting and equipment.

Rock wool insulation is used for hot insulating of piping where disassembly is required such as valve, flange, vessel, tank, pump etc.

Aluminum sheet is used for outer cladding on the insulation of piping.

Materials

Density (kg/m3)

Working temperature (°C)

Thermal conductivity W/(m.K)

Bending  strength (N/cm2)

Compressive strength (N/cm2)

Thermal conductivity calculation formula for reference W/(m.K) 0 : temperature (°C)

Calcium silicate

220

Max. 1000

100°C

0.065

30

45

(0<= θ <=300) 0.0535   +   1.16X10-4X θ (300< θ <=800) 0.0612   +   3 . 3 8 X 10 -5 X θ + 1.95X10-7 X θ 2

200°C

0.077

300°C

0.088

400°C

0.106

500°C

0.127

Perlite insulation

250

Max. 900

0.072

25

25

0.0632  +  1.26X10-4 X θ + 2.67X10-8 X θ2   (0<= θ <=800)

Rock Wool

Density (kg/m3)

Working temperature (°C)

Thermal conductivity W/(m.K) at average temp. 70°C

Thermal   conductivity calculation formula  for reference W/(m.K) 0 : temperature (°C)

Max. 100

Max. 600

0.044

(-20<= θ <=100) 0.0337   +   0.000151 X θ (100< θ <=600) 0.0395  +  4.71X1O-5 X θ   +  5.O 3X1O -7 X θ 2

Health, Safety & Environmental Requirements

Insulation work shall be carried out in accordance with approved health & safety management plan and local environment regulation.

Carry out the work in such a manner as to minimize noise, vibration and other disturbance. Comply with all current regulations and apply all environmental controls.

Necessary barricades, safety signboard and warning lamps shall be installed to warn on cross road between public road and access road.

Safety activities shall be carried out according to the safety plan.

All site engineers and workers will be trained as stated in the safety plan. The contact numbers of the hospital, police station and any other related authorities will be given to engineers to take required actions on the spots.

All workers must wear the standard safety equipment.

Protective equipment should be worn while welding to avoid electric shock.

Minimum safe distance from operating equipment shall be maintained.

General Insulation Application Requirements

Single-Layer shall be installed tight and snug. Two-Layer shall be installed in separate layers arranged as single layer with second layer staggered to the first so as to preclude coincident seams.

Insulation impaled on pins to be retained by speed washers. The pins are then to be bent over against the washers (do not cut pins). Pin standard length is 38mm beyond face of insulation.

Insulation on plate work or burial vault lath to be impaled on pins spaced at approximately 305mm x 305mm centers.

for valves and fittings of 4’’ and larger size, the insulation shall consist of either (a) preformed insulation manufactured to fit the specific fitting or valve or (b) preformed pipe insulation mitered or cut as required to fit the specific fitting or valve.

In either case the insulation thickness and type shall be the same as the adjacent pipe insulation.

Flanged connections on insulated pipe lines shall not be covered until the pipeline has been satisfactorily hydrotested.

Insulation on pipe adjacent to flanges shall be sufficiently tapered back to allow for future removal of flange bolts.

Flanges are to be covered with oversized insulation of the same type and thickness as adjacent pipe insulation and shall lap the pipe insulation by at least 51mm.

The annular space between the flange and pipe covering shall be filled with loose insulating wool.

Insulation covering the flanges shall be installed to permit removal without damage to adjacent pipe covering.

Thermal Insulation and Lagging Procedure

Before installing any insulation material (rock wool slab or rock wool blanket, high temperature rock wool sectional pipe insulation), the entire piping surface shall be cleaned carefully.

Material at adequate thickness shall be well tightened by stainless steel wire for layer by layer. Wire diameter shall be depending upon outer diameter of insulation piping as per the below mentioned table.

Insulation Cover	Wire Diameter
0-150mm	#20 (0.9mmᵠ)
151-400 mm	#18 (1.2 mm?)
401 mm and Above	#16 (1.6 mm?)

After installation of the insulation covers, all the clearance of the joints shall be filled up by the sealing compound of the same quality of the insulation covers.

In case of multi layer installation, every longitudinal and lateral seam lines shall not be located at the same line. The upper longitudinal seam lines shall keep at least 15° away from lower longitudinal seam lines, and set the longitudinal seam lines of each layers upper and keep at least 15° away from lower longitudinal seam lines, and set the longitudinal seam lines of each layers upper and lower shall keep distance more than 100mm.

Lagging sheet (flat aluminum sheet) shall be installed and fixed by tapping screws (pan head) with overlapping more than 15mm along the longitudinal line of the piping.

Outer sheets shall be overlapped downward to prevent any entry of rain water. Set the lateral seam lines, the outer sheet shall be more than 50mm overlapped by swaged joins at the end each sheets, see below figure.

Horizontal and vertical piping shall be insulated with ring supports to prevent any slippage between insulation material and lagging.

Unless otherwise required, ring supports shall be used for all piping of outside diameter exceeding 150A and insulation thickness exceeding 75mm, see below figure.

Outdoor piping shall be insulated with sealing to prevent any entry of rain water from pipe hangers and hanger rods., see below figure.

Each insulated pipe ends shall be covered by the chrysanthemum form, refer below image.

Thermal Insulation of Elbows

Elbows shall normally be insulated by same material of calcium silicate and rock wool pipe cover or blanket used for straight pipe lines.

The material shall be cut according to the bending angle and properly installed in order to prevent big clearance at joint seam lines.

For the insulation material installation on elbows, insulation surface shall be completely cleaned and cutout material along the bending angle shall be properly fitted and tightened by stainless steel wire.

All seam lines of insulation joints shall be completely sealed by the same material of the insulation.

In case of multi layer insulation, each seam lines both longitudinal and lateral shall not be placed on the same position. Each seam lines shall be staggered refer figure below.

On impracticable insulation portion such as socket type elbows, rock wool blankets shall be installed and tightened by using stainless steel wires so as to well fit around the angle.

All seam lines of insulation joints shall be completely sealed by the same material of insulation.

In case of multi layer insulation, each seam lines both longitudinal and lateral shall not be placed at same position. Each seam lines shall be staggered.

For lagging upon the insulated elbows, upper sheet shall be at least 15mm overlapped by fixing with tapping screws (pan head) along the longitudinal line of the piping.

Upper sheet shall be overlapped downward to prevent any entry of rain water.

Lagging for the perpendicular joints from the longitudinal piping line, sheet shall be mitered and swaged by using tapping screws (pan head). Refer below figure.

For the elbows with small bending angle, which is impracticable to apply the standard lagging such as swaged lagging, elbow shape cover or prefabricated lagging cover can be installed.

Insulation of Valves and Flanges

Welded Type Valves

Small Diameter (50 mm and Smaller)

Rock wool blanket shall be continuously installed from the straight pipelines with thickness adjustment of the blanket to keep no connection joints.

Lagging shall also be installed in the same manner to keep a one piece installation without connection joints.

Insulation for Medium Diameter (Size Dia. > 50mm)

To be installed the box-type valve cover prefabricated by the lagging sheet lined with the rock wool insulation material.

Insulation thickness of the box shall be equal to the piping insulation and also lapping dimension between valve cover and insulated piping shall be equal to the piping insulation thickness with keeping one-piece installation manner. See below image.

Thermal Insulation of Flanges

Insulation and lagging shall be installed in the same manner of piping insulation, but connection joints shall be removal types for the repair and maintenance purpose.

For insulation and lagging of flanges, the cylindrical flange cover prefabricated by the aluminum sheet lined by the rock wool.

The clearance between flanges and insulation covers shall be long enough to remove the flange bolts to any directions for repair and maintenance purpose.

The insulated piping and flange covers shall be overlapped each other equal to the piping insulation thickness. Refer below image.

Insulation of Auxiliary Equipment