Hot Thermal Insulation Specification

This article provides you with example hot thermal insulation specification that is used in industrial plant design and construction.

The I4I Academy API RP 571 Damage Mechanisms Affecting Fixed Equipment in the Refining Industry Course, covers corrosion under insulation. The API 510 Pressure Vessel Inspector Course, API 570 Piping Inspector Course, and API 653 Aboveground Storage Tank Inspector Course cover inspection and testing requirements for insulated items.

This Engineering Specification covers the minimum requirements for design and material for external hot thermal insulation of above ground piping and equipment, operating between ambient temperature of 5 °C to 650 °C for the purpose of heat conservation, process stabilization, temperature maintenance, personnel protection, but excludes structural insulation of buildings, fire proofing structures, refractory lining of plants and all external underground mains for use in industrial Plant.

This Engineering Specification define the hot thermal insulation to be used for equipment, and piping system including:

Insulation types.
Insulation materials.
Thickness to be applied.
Fastening materials.
Jacketing systems for insulation protection.
Technical application methods to be used.

1.2. REFERENCES - Hot Thermal Insulation Specification

Throughout this Engineering Specification the latest edition of the following Codes and Standards and Engineering Specifications are recommended:

1.2.1. CODES AND STANDARDS - Hot Thermal Insulation Specification

Mineral fiber preformed pipe insulation ASTM C 547
Mineral fiber blanket thermal insulation ASTM C 553
Mineral fiber blanket insulation and blanket type pipe insulation (Metal mesh covered) ASTM C 592
Mineral fiber block and board thermal insulation ASTM C 612
Wicking type thermal insulation used over Astenic Stainless Steel ASTM C 795
Code of Practice for Thermal Insulation of Pipe Work and Equipment BS 5970 (In the temperature range –100 °C to +870 °C)
Method of Specifying Thermal Insulating Materials on Pipes, Ductwork and Equipment BS 5422 (In the temperature range -40 °C to +700 °C)

1.2.2. ENGINEERING SPECIFICATIONS - Hot Thermal Insulation Specification

Note : Definition of terms used in this engineering specification shall be in accordance with ASTM C 168.

1.3. DESIGN BASIS - Hot Thermal Insulation Specification

1.3.1. TEMPERATURES

Design ambient temperature for hot insulation Tah = +5 °C.

Design ambient temperature for hot personnel protection Tap = +55 °C.

Maximum surface temperature Tse = +65 °C.

The temperature for which the piping is to be insulated shall be the operating temperature indicated on the Line List.

The temperature for which the equipment is to be insulated shall be the operating temperature indicated on the equipment data sheet.

1.3.2. PROCESS REQUIREMENTS - Hot Thermal Insulation Specification

Maximum of calorie losses throughout the hot insulation is depending on the operating / service temperature of the equipment or piping.

Fluid temperature in °C.	100	200	300	400	500	600
Thermal losses in Watt/m2.	112	181	244	304	358	407

1.4. INSULATION TYPES - Hot Thermal Insulation Specification

1.4.1. Heat Conservation (Code H) - Hot Thermal Insulation Specification

In order to maintain a process temperature or for energy saving by reducing the calorie losses.

However, the outer surface of the insulation must be at a maximum temperature of 65°C in normal operating temperature, to ensure personnel protection as defined hereafter.

1.4.2. Personnel Protection (Code P) - Hot Thermal Insulation Specification

For protection of personnel against contact with the hot surfaces, which are operated at temperatures above 65°C in normal operating condition and accessible from normal working areas or access ways and the following clearances:

(1)Within 2200 mm height from ground or floor level.

(2)Within 1000 mm distance beyond the edge of platform or walkway.

In some cases, the insulation may be replaced by a guard consisting of a grid or expanded metal, use of wire guard is subject to OWNER approval.

1.4.3. Heat Tracing

Steam tracing code: T

Electrical tracing code: E

In order to warm up and maintain a process temperature on equipment, piping, instrument etc.

Insulation over size shall be considered for steam tracing (code T) as per Engineering Specification for Steam Tracing.

1.5. INSULATION DATA - Hot Thermal Insulation Specification

1.5.1. Insulation data shall be indicated on the following documents

Equipment insulation: Equipment list
Pipe insulation : Line list

1.5.2. Piping, equipment, storage tanks and vessels requiring insulation shall normally be specified on the following project documents:

Process and Instrument Diagrams (P&IDs).
Piping arrangements and Isometric drawings.
Instruments Piping Details and Schedules.
Vessel, Exchanger, Storage Tank documents and Insulation Schedules.
Equipment supplier’s general arrangement drawings or line list for equipment items in package requiring field insulation work.

1.6. EXTENT OF INSULATION ON PIPING SYSTEM - Hot Thermal Insulation Specification

Insulated piping systems shall have straight pipe, bends, tees and pipefittings completely Insulated.
All valves and flanges joints shall be completely insulated only in steam, steam condensate,hydrocarbon services, hot oil lines and in lines, which are heat traced or jacketed to maintain temperature.
Insulation around valves and instrument shall be provided so that insulation does not interfere its operation.
for bucket and float type steam traps the inlet piping and trap shall be insulated.
Insulation on inlet piping to thermostatic and thermodynamic steam traps shall terminate at approximately 500 mm before the trap.
Steam trap outlet piping other than closed condensate recovery system shall not be insulated except for personnel protection reasons.
Insulation shall be applied over all steam and electrical tracing as per relevant engineering specification.

1.7. EXTENT OF INSULATION ON EQUIPMENT - Hot Thermal Insulation Specification

The scope of insulation for equipment shall be considered in accordance with relevant engineering drawings or vendor drawings.
All equipment shall be insulated for heat conservation as given on insulation schedule and equipment data sheet.
Liquid ends of pumps shall be insulated when heat traced or jacketed or when indicated on outline drawing or on equipment data sheet.
Insulation on exchangers shall be stopped at a sufficient distance from each flange to permit the removal of the flange bolts and shall be finished with a bevel of sealer.
Equipment man ways under 24” shall be insulated with removable cap.

1.8. LIMITATION - Hot Thermal Insulation Specification

1.8.1 hot insulation

The following piping components & equipment shall not be insulated unless otherwise specified.

Visible parts such as nameplate, code inspection plates, stampings, sight glass and level gauge.

2. Shield or guard.

3. Flange connections carrying hydrogen or flammable hydrocarbons with operating temperature above the flash point of media. In this case a rain divert or cover shall be provided on top of flange connection.

4. The following parts of the rotating machinery, which need heat dissipation and cooling, unless otherwise specified.

Stuffing box
Packing ground
Piping and jacket for cooling water
Packing sealed piping
Bearing
Oil cooler
Gear shaft case, etc.

5. Fans, compressors, blowers or other rotating or reciprocating equipment or machinery, unless otherwise specified on relevant data sheet.

6. Down stream piping of block valves without tracing insulation.

7. Safety valves along with its outlet piping and down stream piping of such valves as steam blow off valve, vent and drain valve.

8. Steam traps and the lines down stream of them, which require no recovery of heat of the drain and no prevention of freezing-up, unless specified in the drawing.

9. Parts having moving element, such as expansion and swivel joint, and sliding valves.

10. Support legs and inside of skirts

11. For equipment and piping with inside lining of refractory or insulating material, except for the case where the metal temperature must be controlled.

12. Turbine casing to be insulated shall exclude shaft seal caps, shaft bearing housing, governors and supports.

13. Surfaces of coolers and condensers.

14. Thermo well bosses and pressure tapping.

1.8.2 personnel protection insulation

The following piping components & equipment shall not be insulated unless otherwise specified.

Visible parts such as Nameplate, code inspection plates, stampings, sight glass and level gauge.
Shield or guard.
Flange connections carrying hydrogen or flammable hydrocarbons with operating temperature above the flash point of media. In this case a rain divert or cover shall be provided on top of flange connection.
Safety valves along with its outlet, piping and down stream piping of such valves as steam blow off valve, vent and drain valve.
Support-legs and inside of skirts
For equipment and piping with inside lining of refractory or insulating material except for the case where the metal temperature must be controlled.
Turbine casing to be insulated shall exclude shaft seal caps, shaft bearing housing, governors and supports.
Surfaces of coolers and condensers.
Thermo well bosses and pressure tapping.

1.8.3 clearances

Insulation shall be designed to provide an absolute minimum clearance of 25 mm between the outside surface of any insulation finishing material and adjacent surfaces.
Where insulated piping is supported on steel shoes, the height of the shoe shall be such that the underside of the insulation finishing material is clear of the supporting structure upon which the shoe rest by 25 mm minimum.

1.9. SELECTED INSULATION MATERIALS - Hot Thermal Insulation Specification

1.9.1. GENERAL

All material (Insulation, Jacketing and ancillary material) shall be of high quality, new, and good appearance and shall not have any deleterious action on the surface to be insulated.
Insulation materials shall be packed in a manner, that ensure no moisture can enter during transport, in transit and storage at site. Preferably, the materials shall be fixed to non-returnable pallets.
As much as possible, insulation materials shall be of low chloride content, chemically inert, non-sulfurous, rot proof, vermin proof, impervious to hot water and steam, non-injurious to health and non-corrosive to steel and aluminum (even if soaked in water at ambient temperature for extended periods).

1.9.2. SELECTED MATERIALS - Hot Thermal Insulation Specification

Mineral fibers (glass wool or rock wool) shall only be used.

1.9.3. INSULATION SELECTION - Hot Thermal Insulation Specification

Regarding the insulation, the design temperature shall determine the selection of insulation materials (glass wool or rock wool).

1.9.4. INSULATION THICKNESS - Hot Thermal Insulation Specification

The operating temperature shall be used to determine the insulation thickness.

Multiple layers shall be provided for thickness above 75 mm.

1.9.5. INSULATION TABLES - Hot Thermal Insulation Specification

Annex 1 for heat conservation (Hot) and tracing with mineral fiber.

Annex 2 for personnel protection (Hot) with mineral fibers.

2. MATERIALS FOR INSULATION - Hot Thermal Insulation Specification

Hereafter are listed the required materials and accessories

Insulating materials.
Insulation fastening materials.
Metal jacketing.
Screws …

2.1. INSULATING MATERIALS - Hot Thermal Insulation Specification

2.1.1. HOT AND PERSONNEL PROTECTION INSULATION MATERIALS

Specification and standard application of insulation material for hot and personnel protection services shall be as follows:

The insulation material shall meet the requirements of ASTM C795, when applied on austenitic stainless steel surfaces.
Galvanized wire mesh shall be used up to 370°C operating temperature, and stainless steel wire mesh shall be used above 370°C operating temperature and on austenitic stainless steel surfaces.

2.1.2. COMMERCIAL FORMS TO BE USED - Hot Thermal Insulation Specification

Panels, blankets, blocks, preformed shells, cut shells, slabs …, according to the equipment and pipe sizes and forms.

Preformed insulation shall be used for pipes up to 12” NB.

Insulation materials containing asbestos shall not be used.

2.2. INSULATION FASTENING MATERIALS - Hot Thermal Insulation Specification

2.2.1. Welded Pins (needles)

To maintain insulating materials on storage tank storage shells.

They shall be made of black annealed steel MARTIN type, Dia: 3mm.

2.2.2. Plates

For attachment on needles and handling in place insulating material.

They shall be made of black spring steel.

2.2.3. Wires

They are used to hold pipe insulation materials in place.

Dimensions to be used:

N° 8 (1,3mm.)

Type: TP304 stainless steel

2.2.4. Straps / Fasteners

They shall be suitable for the insulation materials selected and the metal jacketing used.

Type: TP304 stainless steel

2.2.5. Metal Straps

They are used to hold the insulation materials in position on, equipment and materials and where it is no possible to use needles.

Dimension to be used:

Width 12mm for pipes.

Width 19mm for equipment, ducts.

2.2.6. Strap Fasteners

They shall be adapted to the straps on which they are used.

2.3. METAL JACKETING - Hot Thermal Insulation Specification

Aluminum jacketing shall be used as weather protection cover, over the insulation unless otherwise specified.

Thickness and Commercial Form shall be as following tables:

(OD: external insulated diameter of equipment or piping)

Table 1: Aluminum Jacketing Thickness and form For Equipments - Hot Thermal Insulation Specification

Outside Diameter of Insulated Surface	Thickness	Form
OD< 1000 mm	0.8 mm + Min.(1) 0.125 mm Polykraft	Flat Sheet
OD>1000 mm	0.8 mm + Min.(1) 0.125 mm Polykraft	32 mm Corrugated Sheet (2)
Equipment Head and Transitions	0.8 mm + Min.(1) 0.125 mm Polykraft	Flat Sheet

Table 2: Aluminum Jacketing Thickness and form For Piping - Hot Thermal Insulation Specification

Outside Diameter of Insulated Surface	Thickness	Form
OD< 150 mm	0.5 mm+ Min. (1) 0.125 mm Polykraft	Flat Sheet
OD>150 mm	0.8 mm+ Min. (1) 0.125 mm Polykraft	Flat Sheet

Type: ASTM B209 Alloy 3003-H14 or approved equivalent, with factory applied polykraft vapor barrier.

Note 1: The mentioned thicknesses are related to thickness of 0.1 mm kraft sheet and 0.025 mm poly ethylene.

Note 2: Corrugated sheet shall have 32 mm deep corrugations at 32 mm pitch (sinusoidal profile) with provision for maximum end lapping as in the case of a roofing profile

2.3.1. Aluminum Foil

Aluminum foil shall be used to protect Stainless Steel surface.

Thickness shall be: 0.19 mm

For securing Aluminum foil on stainless steel surfaces, Aluminum band 24 SWG thickness with 19 mm wide shall be used.

2.4. Jacket fastening

Blind rivets shall be used for attaching metal jackets together and screws for fixing metal jackets to insulation supports. The material of blind rivets and screws shall be adapted to the material nature of the metal jacketing.

2.4.1. For Attaching Metal Jackets Together

Form: Blind rivet.

Size: Æ = 4mm x 10mm.

2.4.2. For Jacket Fastening To Insulation Supports

Form: Hexagonal heads with washers. (Self-tapping type)

Type: Stainless steel 304 or 304L

Size: Æ = 7 mm. x 13 mm. Long for  < 1500 mm.

Size: Æ = 7 mm. x 19 mm. Long for  > 1500 mm.

Washers: Æ = 19 mm. Neoprene 2 mm. Thickness.

3. INSULATION APPLICATION - Hot Thermal Insulation Specification

3.1. PRECAUTIONS PRIOR TO APPLICATION

The following operations shall be performed on equipment and materials prior to application of insulation:

Supports installation
Satisfactory hydrostatic tests
Preparation of surfaces to be insulated.

If insulation work proceeds in advance of hydrostatic testing and inspection, welded joints shall be left Un insulated until hydrostatic testing is completed.

3.1.1. SUPPORTS INSTALLATION

Generally insulation supports on equipment shall be installed by the Vessel fabricators and on piping by the piping construction contractor. Support field welding on tested equipment or materials, shall be prohibited unless expressly authorized by the engineering contractor.

3.1.2. SURFACE CONDITION

All surfaces to be insulated shall be cleaned in order to remove all contaminates.

Insulation materials shall not be applied to surface, which are wet.

3.2. APPLICATION OF INSULATION - Hot Thermal Insulation Specification

3.2.1. GENERAL

(1) The application methods, given in this engineering specification are general in nature. The construction contractor is responsible for applying an insulating system that to give a satisfactory operational performance and the requirements given herein shall be regarded as the acceptable minimum. The construction contractor shall carryout the work in accordance with the best practices of insulation application with the minimum of waste and debris and the final job shall have a neat, efficient and workmanlike appearance.

(2) Insulation supports shall be provided at least 3700 mm intervals on vertical lines or lines inclined more than 45° from horizontal supports shall be installed above all flanges in vertical lines and located to allow removal of flange bolts.

(3) Before applying weatherproofing, insulation shall be inspected for open joints, voids, cracks and defacing. Open joints, voids, and cracks shall be adequately filled with insulation and defacing made good to the satisfaction of the inspector.

(4) Special consideration shall be given to application of insulation near pipe supports. The insulation and weatherproofing shall be applied in a manner, which does not restrict thermal expansion or contraction of the piping at its support points.

(5) Piping insulation shall be continues at guides.

(6) Inner layers in multiple layer pipe insulation and insulation on irregular equipment surfaces (where use of bands and seals is impractical) shall be secured, using stainless steel wire. The wire shall be drawn taut to imbed it into the insulation. The ends shall be firmly twisted and the excess cut off. The twisted ends shall be bent over and imbedded into the insulation.

(7) Provide expansion spring on vessels over 4500 mm in diameter and operating temperature over 200°C. A minimum of two springs shall be used 180° apart. For each additional 7500 mm of circumference, one additional spring shall be installed. Springs shall be equally spaced around banding.

(8) Provide expansion springs on storage tanks for maximum of every 15 m of circumference.

(9) For equipment 900 mm in diameter and smaller, pipe insulation may be used, where applicable.

(10) For equipment larger than 900 mm in diameter, blanket, blocks, beveled lags or curved segments of insulation shall closely fit the contour of the equipment to be insulated.

(11) Butt and expansion joints shall be staggered for single layer insulation and in both directions all multiple layers of insulation.

(12) Flash all man ways and nozzle necks and seal to prevent entry of water.

(13) Support lugs for ladders, platforms, piping, etc. shall be flashed and pointed.

(14) Double pipe exchangers (if any) shall be insulated as a unit.

(15) Hydrostatic tests on pipe, vessels and equipment, if possible shall be completed before insulation is installed. If insulation is applied before testing, all weld and thread joints shall be exposed until completion of testing.

(16) Care shall be taken to avoid contact between dissimilar material which might causes galvanic corrosion.

(17) All insulating, finish coatings, fabrics, mastics and sealant material shall be asbestos free.

(18) Insulation, which needs to be removed for maintenance purpose, shall be fabricated in such a manner, that it is easily removable and can be remounted with a minimum of work. Quick opening boxes and similar construction shall be used in this case.

(19) Single thickness sectional pipe insulation shall be applied with longitudinal joints staggered and shall be secured with wire ties on 230 mm centers. Double thickness sectional pipe insulation shall be applied with all joints staggered and shall have inner layer secured by at least two wires per section with the outer layer secured by wire ties on 230 mm centers.

(20) External stiffing rings on vessel and piping shall be insulated with the same thickness as required for vessel or piping.

3.2.2. APPLICATION OF INSULATING MATERIALS

Only sound and dry materials having the correct dimensions, and the required quality shall be installed.
Cut outs in insulation shall be clean cut.
Basic rules for installation of insulation components on equipments, ducts, piping, and instruments, to prevent calorie losses through the joints, is the staggered arrangement.
When more than one layer is provided, the components of each layer shall be staggered and joints of the second layer shall be off set from those of the first layer
Blanket (metal-mesh covered) shall be secured by twisting together the wire mesh or by means of a hook or by tying them together with 0.8 mm diameter wire.
Any beveled or rounded edges of insulating component shall be carefully square off before application.
Each layer of insulating panels shall be impaled on welded pins held by means of quick tightening plates.
10 pins/m2 are required and shall be welded with staggered arrangement.
Each layer of insulating blanket shall be applied on circular equipment and secured by steel wire or adapted straps with an adequate spacing to hold components in place. (Maximum spacing: 250 mm from center to center).
On any sharp angles, a small alloy aluminum angle piece shall be installed to prevent the metal strap cutting into the insulating materials.
On bottom of equipment, or around accessories (such as nozzles, manholes, supports, etc.) a floating ring shall be used to fix straps.
All insulation components shall be carefully cut and adjusted to follow the exact shape of surfaces, nozzles, manholes, rings, supports, gussets …
Stiffeners shall be thoroughly insulated to the required thickness.
All spaces between blocks or between insulation and equipment shall be completely filled and packed with a flock wool material.
A layer of aluminum foil shall be wrapped around stainless steel equipment and piping to eliminate chloride attack from hot insulating mineral wool

3.2.3. APPLICATION OF THE METALLIC JACKETING

After equipment or piping insulation has been applied in a satisfactory manner the insulation shall be immediately jacketed and waterproofed.
If bare insulation cannot be jacketed before the end of the working day the system shall be protected with plastic sheets or in shed to prevent water entering.
A basic rule concerns the orientation of the metal jacket overlapping.
To prevent any ingress of water (or other liquid) under the jacket, it is essential for horizontal joints, that the top sheet overlaps the bottom sheet (like roof tiles).
In the case of vertical joints the overlap shall be in opposite direction of the prevailing wind.
Laps shall be swaged to increase stiffness and seal efficiency.
On equipment, ducts, piping and whenever it is possible, both horizontal and vertical laps shall be minimum 50mm wide, otherwise, they shall be as large as possible.
Metal jackets shall be fixed together by adequate screws spaced of maximum 200mm. From center to center.
To prevent thermal bridges, insulating fabric bands shall be provided between jacket and support on equipments and at insulation supports.
• To allow movement due to the differential expansion between equipment or piping and jacket, special arrangement shall be provided (Example: a circumferential lap joint located between 2 supports shall not be fixed).
On accessories such as supports, branch connections, nozzles, manholes … where adjustment of jacket is difficult and water infiltration is most likely to happen finishing sheet in 2 parts attached by screws, lapped and swaged shall be provided. Sealing mastic shall also be used.
Jacket for vessel heads shall be in section except for small diameters where they may be either flat or Chinese hat type.
In some cases (like for pumps) the metal jacket may be replaced by mastic coating with wire mesh and glass cloth reinforcement (or by fiber glass reinforced epoxy coating).
The outer surface of insulation shall have a regular and smooth finish.

3.2.4. INSULATION OF EQUIPMENTS AND DUCTS

Insulation shall be applied in conformity with the recommendations of the paragraph 3.2.2.

Insulation elements like blocks and slabs shall be applied with their length parallel to the greatest length of surface being covered.

The base course shall be applied with alternate length blocks so that all successive end joints are staggered.

Skirts supporting equipments shall be insulated outside as part of the equipment area.

The insulation shall extend downwards, from the junction of the inside of the skirt and the insulated equipment to a distance of three times the thickness of insulation but in no case less than 250mm.

The thickness of the insulation shall be equal to that specified for the equipment.

Full insulation thickness shall be applied over all support rings, stiffeners, and other protuberencies on the surface of equipment.

Vessel identification plates shall not be insulated.

Finally metallic jacketing shall be applied.

3.2.5. INSULATION ON PIPING - Hot Thermal Insulation Specification

Insulation shall be applied in conformity with the recommendation of the paragraph 3.2.2.

Straight Pipes

The edges of pipe insulation segments shall be cut off square leaving a distance between the insulation segment edge and the flange bolt extremity equal to the bolt length plus 25mm. To ensure enough clearance for bolt dismantling.

On valves, stuffing boxes shall not be insulated.

Bends

Generally, materials shall be cut into suitable segments and joints shall be carefully staggered.

Each section shall be held in position by a metal strap and fastener.

Tees and Branch Connections

Elements shall be carefully cut and adjusted.

When two layers (or more) of insulation are provided, joints shall be staggered as follow:

1st layer on secondary branch
1st layer on main pipe
2nd layer on secondary branch
2nd layer on main pipe.

Then metallic jacketing shall be applied.

Flanged Components

If insulation is required, flanged components shall be insulated by means of prefabricated boxes or insulation elements like blocks and slabs.

3.2.6. INSULATION ON INSTRUMENTS - Hot Thermal Insulation Specification

For in-line instruments, level gauges and up to block valve of local instruments such as pressure gauges, extend and specification of insulation shall be according to this engineering specification.

For lubing impulse / analyzer line, insulation extend and specification shall be in accordant with Engineering Specification for Control and Instrument.

Generally local instruments shall be insulated by means of prefabricated removable boxes or insulation elements like blocks and slabs.

Insulation shall be applied as described in paragraphs 3.2.1 to 3.2.3 for instrument pipes.

Insulation must enable controls and adjustments.

3.2.7. INSPECTION WINDOWS - Hot Thermal Insulation Specification

Adequate number of inspection windows on all strategic locations shall be provided for checking metal corrosion by construction contractor, which will be specified by field engineer.

The removable window shall be of the same basic material and thickness as the rest of the insulation and of sufficient rigidity to withstand handling.

4. STORAGE - Hot Thermal Insulation Specification

Insulating materials shall be packed in a manner that ensure no moisture can enter during transport, in transit, and storage at site.

Preferably, the materials shall be fixed to non-returnable pallets.

ANNEX 1 - Hot Thermal Insulation Specification

HOT INSULATION

HEAT CONSERVATION AND TRACING (CODES H, T and E)

INSULATING MATERIAL: MINERAL WOOL

OUTDOOR EQUIPMENT AND MATERIALS

AMBIENT TEMPERATURE : 5°C

Wind velocity : 10 m/s

Jacketing emissivity : 0.9

INSULATION THICKNESS TABLE (mm)

Pipe Diameter	Pipe Diameter	OP	OP	OP	OP	OP	OP	OP	OP	OP	OP
Nominal (NPS)	Outside (mm)	0°C to 50°C	51°C to 100°C	101°C to 150°C	151°C to 200°C	201°C to 250°C	251°C to 300°C	301°C to 350°c	351°C to 400°C	401°C to 450°C	451°C to 500°C
¼”	13.7	20	30	30	30	40	40	40	50	50	60
½”	21.3	20	30	30	40	40	50	50	50	60	70
¾”	26.7	30	30	40	40	40	50	50	50	70	80
1”	33.4	30	30	40	40	50	50	50	60	70	80
1 ½”	48.3	30	40	40	40	50	50	60	60	80	90
2”	60.3	30	40	40	50	50	60	60	70	80	100
3”	88.9	30	40	40	50	50	60	60	80	90	110
4”	114.3	30	40	50	50	60	60	70	80	100	120
6”	168.3	30	40	50	50	60	70	80	90	110	130
8”	219.1	30	40	50	60	60	70	80	100	120	140
10”	273.1	30	40	50	60	60	70	80	100	120	140
12”	323.9	30	40	50	60	70	70	90	110	130	150
14”	355.6	30	40	50	60	70	70	90	110	130	150
16”	406.4	30	50	50	60	70	70	90	110	130	160
18”	457.2	30	50	50	60	70	70	90	110	140	160
20”	508	30	50	50	60	70	80	90	120	140	160
24”	609.6	40	50	50	60	70	80	100	120	140	170
30”	762	40	50	50	60	70	80	100	120	150	180
34”	863.6	40	50	50	60	70	80	100	130	150	180
36”	914.4	40	50	50	60	70	80	100	130	150	180
40”	1016	40	50	60	60	70	80	100	130	160	190
42”	1066.8	40	50	60	60	70	80	110	130	160	190
Flat Surfaces and over 42” pipe	Flat Surfaces and over 42” pipe	40	50	60	70	80	90	110	140	170	210

ANNEX 2 - Hot Thermal Insulation Specification

HOT INSULATION

PERSONNEL PROTECTION (CODE P)

INSULATING MATERIAL: MINERAL WOOL

OUTDOOR EQUIPMENT AND MATERIALS

AMBIENT TEMPERATURE : 55°C

MAXIMUM SURFACE TEMPERATURE : 68°C

Wind velocity : 2 m/s

Jacketing emissivity : 0.9

INSULATION THICKNESS TABLE (mm)

Pipe Diameter	Pipe Diameter	OP	OP	OP	OP	OP	OP	OP	OP	OP	OP
Nominal (NPS)	Outside (mm)	0°C to 50°C	51°C to 100°C	101°C to 150°C	151°C to 200°C	201°C to 250°C	251°C to 300°C	301°C to 350°c	351°C to 400°C	401°C to 450°C	451°C to 500°C
¼”	13.7	20	30	30	30	40	40	40	50	50	60
½”	21.3	20	30	30	40	40	50	50	50	60	70
¾”	26.7	30	30	40	40	40	50	50	50	70	80
1”	33.4	30	30	40	40	50	50	50	60	70	80
1 ½”	48.3	30	40	40	40	50	50	60	60	80	90
2”	60.3	30	40	40	50	50	60	60	70	80	100
3”	88.9	30	40	40	50	50	60	60	80	90	110
4”	114.3	30	40	50	50	60	60	70	80	100	120
6”	168.3	30	40	50	50	60	70	80	90	110	130
8”	219.1	30	40	50	60	60	70	80	100	120	140
10”	273.1	30	40	50	60	60	70	80	100	120	140
12”	323.9	30	40	50	60	70	70	90	110	130	150
14”	355.6	30	40	50	60	70	70	90	110	130	150
16”	406.4	30	50	50	60	70	70	90	110	130	160
18”	457.2	30	50	50	60	70	70	90	110	140	160
20”	508	30	50	50	60	70	80	90	120	140	160
24”	609.6	40	50	50	60	70	80	100	120	140	170
30”	762	40	50	50	60	70	80	100	120	150	180
34”	863.6	40	50	50	60	70	80	100	130	150	180
36”	914.4	40	50	50	60	70	80	100	130	150	180
40”	1016	40	50	60	60	70	80	100	130	160	190
42”	1066.8	40	50	60	60	70	80	110	130	160	190
Flat Surfaces and over 42” pipe	Flat Surfaces and over 42” pipe	40	50	60	70	80	90	110	140	170	210

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