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Table of Contents

Page

1. Introduction 1

2. What is metal jacketed gasket 1

3. Products being considered 1

4. Storage precautions 1

5. Precautions for selection and design 2

5.1 Precautions for selection

5.2 Precautions for design

6. Precautions before mounting 3

6.1 Flange condition

6.2 Gasket seating surface on flange

6.3 Bolts & nuts

7. Precautions during gasket replacement 4

8. Precautions during installation 5 ~ 6

8.1 Gasket installation

8.2 Bolt tightening

9. Precautions on gas sealing 6

10. Precautions on disposal 6

10. Other precautions 6

Note:

(1) We have examined the contents of this manual thoroughly. However, found any doubtful points or noticed any errors,

omissions, etc., please let us know.

(2) Please forward your questions and consultation about the contents of this manual, or request for catalogues, etc.

to the following.

NICHIAS Corporation

Publication Post

6-1, Hatchobori 1-Chome Chuo-ku, Checked

Metal Jacketed Gasket Instruction Manual

Section: Industrial Product Division

Technical Service & Development Group

Reported by

28-Nov-13

Tokyo 105-8555, Japan

Approved

TayReference

No.

Date of Issue

G-GR-133-0

28-Nov-13

H. Shibata

M. Hiratsuka

(1/5)

1. Introduction

This instruction manual is intended to ensure proper use of metal Jacketed gasket, to present precautions on

selection and design, mounting, storage, disposal.

Please use it carefully after reading this manual.

Please do not use the metal jacketed gasket for a purpose other than gasket use.

2. What is metal jacketed gasket

A metal jacketed gasket is a gasket that has an inorganic heat-resistant cushion covered by a thin metal plate. It is

manufactured in various shapes and covering methods depending upon the intended application and the location

where it is used. It is used for high temperature coupling flanges and manholes, etc. for heat exchangers,

pressure vessels, towers and vessels, equipments, valves, and so on.

Metal jacketed gasket that expanded graphite sheet is applied to the gasket surface in order to improve

conformability against the flange surface is also available.

3. Products being considered

This instruction manual was prepared by considering the following metal jacketed gasket.

Tombo No. : 1841 series, 1861 series

4. Storage precautions

Please note the following points when storing the gasket.

・Store the gasket without unpacking it in a cool and dark place indoors. The storage period shall be 3 years as

a guide. Please consult us if storage period is more than 3 years.

・Do not bend, twist, push or pull a gasket.

・Do not place any object on the package or walk over the package.

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5. Precautions for selection and design

5.1 Precautions for selection

・Select the gasket which shape, size, flange & bolt strength and gasket seat type & size are suitable for the

usage condition

・Select material that can withstand operating temperature, pressure and fluid sufficiently.

・If the service temperature is 400℃ or lower, the use of the TOMBO No.1891 (kammprofile gasket) is

recommended. It can get a good conformability against the flange and ensures a stable sealability compared

to metal jacketed.

・The use of a metal jacketed gasket is not recommended for a standard pipe flange since it is difficult to get

enough tightening force. If it is necessary to use a metal jacketed gasket, the use of one with hangers is

recommended.

5.2 Precautions for design

・Design the gasket width (sealing width) for flat type should be 10mm or more (corrugated type should be

15mm or more) and 25mm or less.

・Gasket thickness shall be 3.0mm as standard thickness.

・ Use suitable flange material, bolt material and bolt size that have sufficient strength to give a required tightening

stress on the gasket. Also, consider the flange structure and quantity of the bolts to get uniform distribution of

the seating stress.

・ Please avoid large bending stress, repeating thermal stress or vibration on the flange. It will reduce the

tightening stress and these can cause leakage.

・ Choose type B and design the dimension since type B is better sealability than type A when the gasket is used

in RF type flange. In this case, the gasket with hangers is recommended for centering function.

・ Don't make a bolt hole generally when the gasket is used in FF type flange. Please choose ring type gasket

which is placed inner side of bolt holes.

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Type A Type B

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6. Precautions before mounting

When mounting the gasket, please note the following items to prevent leakage.

6.1 Flange condition

・Lack of parallelism between flanges facing each other could result in uneven tightening. Place them in the

correct position (See Figure 1).

・Gaskets are not matching to each other when there is a gap between axes of flanges facing each other. Place

them in the correct position (See Figure 2).

・Having a large space between flange faces provides a small pressure between gasket faces even when a large

clamping force is given to bolts, and could cause leakage. Address the problem appropriately (See Figure 3).

・Deformation of flanges will result in an incorrect contacting pressure and may cause leakage. Replace the

flange or address the problem appropriately (See Figure 4).

6.2 Gasket seating surface on flange

・If depressions, projections or rust are found on gasket seating surfaces, Replace the flanges and correct to the

flange surface roughness to the prescribed profile irregularity.

・If cracks penetrating from the inner periphery to the outer periphery are found, polish them.

6.3 Bolts & nuts

・Remove foreign matters, rust, burrs, etc. from bolts and nuts before use. Clean them again or replace them

when a nut cannot be tightened by hand to the end of the threaded portion.

G-GR-133-0

Figure 1: Bad parallelism Figure 2: Gap between axes

Figure 3: Large Space between

Flange Faces

Figure 4: Deformation of flanges

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7. Precautions during gasket replacement

If you are replacing gasket of existing equipment, please install new gasket after completely removing old gasket

as follows:

・Remove the old gasket by using scraper or wire brush while applying water or dust preventing agent. Be careful

not to damage the gasket seating surface then.

・Do not damage or bend gaskets during installation and storage period.

・Removed gaskets must be immediately treat as industrial waste.

8. Precautions during installation

8.1 Gasket installation

・Check tags, labels, etc. to make sure that the material and the dimension of gaskets are suitable for the place

where gasket are used before installing them to flanges.

・Apply gasket paste to the gasket surface when the gasket is used for gas type fluid. Never-Seez® is

recommended as gasket paste.

・Do not leave any foreign material between flanges and gaskets.

・Insert the gasket with sufficient space between flange faces. If you push the gasket by force, it may cause

damage. Confirm the gasket is placed in not offset position but "correct position" after insert the gasket.

・When using a metal jacketed gasket in a T&G type flange, install the gasket so that the face which has turned

gasket edge touch the inside of the groove flange as in figure 5.

・Use the bolt that high tightening torque can be applied.

・Use insuration on the inner side of gasket to prevent the corrosion of the gasket by high temperature.

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Figure 5: Drawing of installation when using a metal jacketed gasket in a T&G type flange

Correct installation example Wrong installation example

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8.2 Bolt tightening

Insufficient tightening, uneven tightening, and over tightening will degrade the performance of gaskets. Tighten

them appropriately as shown below.

(1) Check that the material and size of bolts are appropriate.

(2) Apply a light coat of a lubricant on the threaded portions of bolts and nuts and on washers of nut bearing

surfaces.

(3) Calculate the tightening torque required for bolts from the contacting pressure required for gaskets.

(4)Tighten bolts from side to side around the joint in a star like crossing pattern (See Figure 6).

All bolts should be tightened in four to five increments, according proper bolting patterns. Immediate tightening

can cause leaks and compression damage.

(5) When starting or restarting an operation, tighten again with the initial tightening torque.

(6) When a leakage happen, remove the fluid pressure and tighten again to the initial tightening torque. If the

leakage does not stop after tightening the bolts again, replace with new gaskets.

The above mentioned tightening method is based on the guide of tightening flange joints of ASME PCC-1.

There is another guide for tightening joints, that is JIS B2251-2008*. Use one of the above mentioned methods

for tightening.

*: This is a standard for bolt tightening procedure for flanged joint assembly. This is applicable to joint sheet and

spiral wound gasket.

9. Precautions on gas sealing

When using a metal jacketed gasket for a gas type fluid, use it together with GRASEAL™ (expanded graphite) tape

or gasket paste such as Never-Seez® (service temperature range: -183 to 1425℃) ,etc.

10. Precautions on disposal

When disposing gasket and the used waste products, do not incinerate them but dispose as waste pursuant to

Waste Management and Public Cleaning Law according to your respective country.

11. Other precautions

Check the precautions for occupational health using the MSDS (product safety data sheet).

G-GR-133-0

Figure 6: Examples of tightening 8 bolts