Are Gaskets at Heat Exchanger Girth Flanges considered as Pressure Parts. 1

[DK44]

1. Different types of Gaskets are used at Bolted Girth Flanges of Hear Exchangers designed to ASME SEC VIII Div 1, as well as at Standard Nozzle Flanges. They are listed at ASME SEC VIII Div 1 Table 2-5.1, ASME B 16.5, ASME B 16.20. Are these gaskets considered as pressure parts.
2. Are these gaskets supplied with Certificate to 3.1 of EN 10.204
3. What is the scope of Inspection / certification.

 

[BJI]

1. Yes
2. No, see 3.
3. None, unless specifically ordered

 

[DK44]

BJI. Do you mean, the Gaskets are pressure parts. But no code or standard covers the method of calculation of thickness and sizing of gaskets for Pressure loads!

 

[BJI]

Scary isn't it. Well ASME B16.20 and B16.21 cover standard metallic and nonmetallic gaskets, and this includes performance testing criteria that the manufacturers are required to meet, but whether this is followed and how often gaskets are tested is another matter. Provided these are followed, then most of the design is grandfathered into the codes, however, not all sizings are optimal and some are pretty poor. For custom gaskets there is no guidance, some minor calculations can be performed but most comes down to experience, often left up to the gasket manufacturers. You can always specify compression testing requirements when ordering more critical spiral wound gaskets, for example.

 

[DK44]

From the above, can we conclude that the Gaskets are non pressure parts?
I sincerely invite comments from other experts also on this subject.

 

[XL83NL]

Hi DWARAKAKRISHNA, based on your previous topics & posts, I suspect you ask this question in view of the PED 2014/68/EU, and the definition which the PED uses for pressure parts. Is that correct? That would shed a whole different light on this topic.

 

[DK44]

Daer XL83NL.
My question is not in reference to PED. It is an independent question. But surprisingly, being unaware of it I understand now from your observation, it has some relevance to PED.
Ignoring PED link, I want to know whether a gasket can be considered as a pressure part (pressure bearing part for that matter) or not.

Also I want to know whether EN 10204 3.1 certification pertains to pressure parts only.

 

[Vikko]

Gasket are definitely not pressure parts.

Usually it is meant for:
- pressure parts: vessel, cylinder, head, cap, nozzle, flange, tubesheet, dished end, shell, tube, pipe, plug, elbow, fitting, and so on.
- non pressure parts: baffles, impingement plate, support plate, support bracket, tie rod, tube spacer, saddle, skirt, frame, and so on.

Gasket should never be designed alone without considering all the joint together made by flange/tubesheet/gasket/bolt/cover/nut.
The rules for design of joints can be found in:
- ASME VIII Div 1 Appendix 2
- EN 13445-3 11
- EN 13445-3 Annex G
- EN 1591

Standard gasket for standard flange are in:
- EN 1514
- EN 12560
- ASME B16.20
- ASME B16.21

 

[DK44]

It gives me to understand as:
1. Gaskets as used in Pressure Vessels and Heat Exchangers are non pressure parts.
2. They are meant for achieving leak tightness at mechanical joints ex: bolted flange joints, under fluid pressure. When such joints are tightened, some amount of gasket flexing / yielding occurs as the gasket adjusts into the minute surface irregularities and unevenness of mating contact faces of flanges without itself being crushed, to achieve leak tightness under pressure.
3. Design of gaskets itself and sizing as a pressure part is not covered by pressure vessel codes.
Particular types are selected as recommended in codes with proper strength factors (ex: m&y of ASME) and assessed for seating stress in flange design.
4. We can procure the gaskets like SPW, MJA, Solid Metal etc with TPIA with proper scope.
Comments are invited.

 

[Dhurjati Sen]

Dear Dwarakakrishna,

Do you use the original gaskets for hydro-tests? You don't. So gaskets are not pressure parts, they are as per your understanding (refer your last post)

Regards.

DHURJATI SEN

 

[DK44]

DHURJATI SEN.
Flanged joints are to be proved leak tight with original gaskets only and then the joints are not dismantled.
However gaskets are not pressure parts as per my understanding noted previously.