Comparison of Semi-Metallic Gasket’s
Performance andIntroduction of Kammprofile Gasket Series
1. Introduction

JIS B 2490. The paste（No. 6）was applied to the metal
jacketed gasket based on the general usage.
Sealing performance of the spiral wound gasket wasenergy, semi-metallic gaskets such as Spiral Woundthe best at room temperature. The kammprofile

Gaskets, Metal Jacketed Gaskets, and Kammprofile

gasket and metal jacketed gasket have a large

Gaskets are often used.

amount of leakage at low gasket contact stress（12.5-50

Spiral Wound Gaskets are widely used from piping toMPa）, and when loaded with 50 MPa or more, theequipment, and Metal Jacketed Gaskets are often used inleak amount is less than the measurement sensitivity.

equipment such as heat exchangers because they have a

The sealing performance is higher than the detection

narrow seal width and can make branched gaskets. The

level of the soap bubble test used for the leakKammprofile Gaskets have been widely used overseas,

detection at the plant.

but in recent years, it is becoming popular in Japan

Contact gasket stress［MPa］ Test conditionsSeal test method
No.6596V_t4.5
Sample Dimension
No.6540H_t4.0
Internal pressure
No.N520_t3.0_Gasket Paste
Range of measurement
No.6 applied

because of its excellent performance and due to easy
handling.

：JIS B 2490
：JIS 20K 50A：4.0 MPa (He)
：1.7×10 －5 ～ 1.7×10 －1 Pa･m3/s

No.38

way, but with the aging of equipment and thediversification of attitudes toward maintenancemanagement, they have come to be re-selectedaccording to usage conditions. However, there are few
performance comparison data for these semi-metallic

Leak rate［Pa・m3/s］

Though semi-metallic gaskets have been used in thisDetection level ofsoap bubble test

gaskets. Therefore, this report presents comparativeevaluation data of semi-metallic gaskets which provide
an indicator for users to select gaskets. At the sametime, we will introduce the features of the Kammprofile

Contact gasket stress［MPa］

Winter 2020

In the fields of petroleum refining, petrochemical, andTest step

Figure1

Room Temperature Sealing Performancegasket series which expanded our lineup.

2-2）Compression and recovery characteristics

This study was conducted with Spiral Wound Gasket

Figure2 shows the compression and recovery（No.6596V）
using expanded graphite, Kammprofile Gasket

characteristics. The difference in the amount of gasket（No.6540H）, and Metal Jacketed Gasket（No.N520）.

displacement between the contact gasket stress at 5
MPa and 100 MPa was defined as the amount of

2. Comparative evaluation

compression. The difference in the amount of gasket
displacement between the contact gasket stress at 1002-1）Sealing performance at room temperature

MPa and 12.5 MPa was defined as the amount ofFigure1 shows the sealing performance at room

recovery. Table 1 shows the compression and recovery

temperature. The evaluation was performed based onamounts of gaskets.

15Technical Papers

Table1 shows that the spiral-wound gasket had theheating was less than the measurement detection

largest amount of compression and recovery. For thelevel, but the leak amount increased after the heating.

metal jacketed gasket, the compression amount wasThis is thought to be due to the decrease in thelarge but the recovery amount was small, and for theresilience of the core material due to repeated thermal

kammprofile gasket, both the compression amount andcycles.

the recovery amount were small. If the flange gap
fluctuation is large due to thermal cycling, a spiralwound gasket with the best compression recovery

No.6596V（Contact stress70 MPa）

No.6540H（70 MPa）

No.6596V（50 MPa）

No.6540H（100 MPa）

Sample Dimension ：JPI Class300 2B
No.N520（70 MPa）
Heating temperature ：400 ℃（Applied No.6） Heating time：15 hours
Internal pressure ：4 MPa（N2）Seal test method ：S ubmersion
methodRange of measurement ：0.1～5000 cc/min

characteristics isappropriate.

t4.5

Compression［mm］Recovery［mm］
Contact gasket stress Contact gasket stress
5 MPa → 100 MPa 100 MPa → 12.5 MPa
0.850
0.198

No.6540H t4.0
No.N520 t3.0
（Applied No.6）
No.6596V_t4.5

0.432

0.060

0.918

0.079

Test conditions
Sample Dimension

No.6540H_t4.0

Reak rate［cc/min］

No.6596VCompression recovery characteristics

Leak rate［Pa・m3/s］

Table1：JIS 20K 50A

Before Heating

Figure3

1 cycle3 cycle5 cycleThermal Cycle Sealing Performance at 400℃

No.6540H（Contact stress70 MPa）

No.N520（70 MPa）（Applied No.6）

No.6540H（100 MPa）

Sample Dimension		

：JPI Class300 2B

Heating temperature：500 ℃

Heating time		

：15 hours

Internal pressure		：4 MPa（N2）Seal test method 		

: Submersion method

Range of measurement ：0.1 ～5000 cc/min

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Displacement［mm］

2-3）‌Sealing performance at high-temperaturethermal cycling

For evaluation of sealing performance at hightemperature, heating and cooling are repeated while
the gasket was tightened to the flange and evaluation

Reak rate［cc/min］

Compression Recovery Characteristics
Leak rate［Pa・m3/s］

Figure2

was carried out after cooling.
Figures3 and 4 show the sealing performance with thethermal cycle. The tightening contact gasket stress
was set to 70 MPa for all samples, and therecommended tightening contact gasket stress for

Before HeatingFigure4

1 cycle3 cycleWinter 2020

Contact gasket stress［MPa］

No.N520_t3.0_Gasket Paste
No.6 applied

5 cycleThermal Cycle Sealing Performance at 500℃

each gasket was also used. The heating temperature
was 400℃ and 500℃ .

2-4）Selective use of semi-metallic gaskets

From Figure3 and 4, the spiral wound gasket and theSpiral wound gaskets are the best semi-metallickammprofile gasket maintained stable sealing

gaskets in terms of performance. However, it may beperformance. On the other hand, in the case of the

difficult to use the spiral wound gasket, such as ametal jacketed gasket, the leak amount before thelarge diameter which is difficult to handle and a shape16Comparison of Semi-Metallic Gasket’s Performance and Introduction of Kammprofile Gasket Series

witha narrow gasket width. Therefore, when theheating temperature was increased, but the leakage

diameter of the gasket is less than about φ1000 mm

amount of No.6540H increased significantly. This isand the seal width can be secured, the spiral woundbecause expanded graphite disappears due togasket is appropriatee. On the other hand, when aoxidation.Since the expanded graphite graduallylarge diameter（φ1000 mm or more）and seal widthoxidizes and disappears above 400℃ , long-termcannot be secured, or when working at high places, asealability maintenance is a concern. Figure6 and 7

kammprofile gasket or metal jacketed gasket

show the rate of weight loss over temperature andisappropriate. Also, metal jacketed gaskets have thetime for expanded graphite sheet and VALQUA

advantage that they can be processed into various

HEAT RESIST SHEETTM. Figure7 shows the evaluation

shapes such as ellipses and rectangles and are more

result of up to 240 hours. However, the expanded

economical than kammprofile gaskets.

graphite decreases even at temperatures of about
400℃ to 500℃ , the sealing stability is a concern in the3. Kammprofile gasket series

long term of 2 to 4 years. The VALQUA HEAT RESISTSHEETTM loses a little weight at the beginning ofWinter 20203-1）Features

heating, and most of it remains unchanged in the long

As previously stated, the kammprofile gasket isterm. In addition, even if the heating temperature isbecoming increasingly spread in Japan in recent

raised, the rate of decrease remains unchanged, andyears. In response, we have developed a new profile

the rate of decrease in the long term is also constant,gasket and expanded our product lineup. According toresulting in stable sealing.

the usage conditions, it became possible to select theNo.6540H（Contact stress 100 MPa）

surface layer material to be bonded to the metallic
serrated gasket.

No.HR540H（100 MPa）

Expanded graphite sheet laminated productSample Dimension ：JPI Class300
Heating temperature：600 ℃

Heating time：15 hours

2B

Internal pressure：0.5 MPa（N2）Seal test method：Submersion method

Range of measurement ：0.1 ～ 5000 cc/min（No.6540H）is a general-purpose product that can behigher which is a temperature range in which
expanded graphite is liable to disappear by oxidation,
the more heat resistant VALQUA HEAT RESISTSHEETTM laminated product （No.HR540H） isappropriate. PTFE sheet laminated product（No.7540H）
is used at lower temperatures than the expanded

Reak rate［cc/min］

used under various conditions. When used at 400℃ or
Leak rate［Pa・m3/s］

No.38

graphite product, but it is appropriatefor lines where
it is difficult to use expanded graphite due to theconcern of contamination.

BeforeHeating

Figure53-2）Characteristic evaluation

1 cycleAfter
retightening

2 cyclesThermal Cycle Sealing Performance at 600℃

Heat resistance is one of a features of No.HR540H.

Large diameters pipe flange connections or equipment

Figure5 shows the thermal cyclic characteristics atmay be subjected to flange rotation, etc., and the gasket

600℃ of a kammprofile gasket with a surface layer amay have a load greater than the recommended

TMVALQUA HEAT RESIST SHEET

and an expanded

tightening contact stress. Therefore, there is a concern

graphite sheet.

that the metal part is exposed at the time of tightening

From the results at 600℃ , the leakage amount ofand may damage the flange. Table2 and Figure8 show

No.HR540H did not change significantly even when thethe evaluation results of kammprofile gasket’s surface

17

Technical Papers

material which is cracked by applying excessive
contact gasket stress. In No.HR540H and No.6540H, noNo.HR540H

200 MPa

No.6540H

200 MPa

No.7540H

140 MPa

metal exposure was observed even when a contact
gasket stress of 200 MPa was applied, and there is alittle risk of damaging the flange even if an excessive
contact gasket stress was applied. In No.7540H, metal
exposure was confirmed at a contact gasket stress of
140 MPa. This is probably because the PTFE sheet iseasier to flow than the expanded graphite sheet.
However, the recommended tightening contact gasket
stress of No.7540H is 60 MPa, and even if a contact
gasket stress twice as high as the recommended tightening
contact gasket stress is applied, no metal is exposed
and it is considered that there is no problem in use.

Winter 2020

Weight loss rate［%］VALQUA HEAT RESIST SHEETTM Heating time：72 hours
（In the air）
Expanded graphite sheet

Heating temperature

Figure6

Change in weight loss rate with temperatures
VALQUA HEAT RESIST SHEETTM
Expanded graphite sheet

Heating temperature：550℃
（In the air）Figure8

Appearance after excessive contact gasket stress

4. Conclusion

Weight loss rate［%］In domestic petroleum refining and petrochemicalplants, more stable sealing products are required dueto the aging of plants and the prolonged periodic
maintenance. We hope the performance comparison ofthese semi-metallic gaskets and the kammprofile
gasket series will be an good option in selectinggaskets.
Heating time［hour］

Figure7

Change in weight loss rate with times

Table2

Change in weight loss rate with times

Sample Dimension
VALQUA HEATRESISTSHEETTM
Expanded graphite
No.6540Hsheet

No.HR540H

No.7540HPTFE

sheet

Metal exposure
No metal exposure at
200 MPa
No metal exposure at
200 MPa
metal exposure at
140 MPa

Satomi Takahashi
Corporate Research andDevelopment Group
Product Development
Division
18No.38