Anindya

The requested paper has been emailed to you.
As to the AD-merkblatter:

1.Scope of the AD-Merkblatter
The AD-Merkblatter are approx. comparable to ASME BPVC Sect. VIII Div.1

2. Leakage
The latest version AD-2000 does not deal with leakage analysis of bolted flange connections.
For flange analysis AD-2000 refers to DIN 2505. AD-2000 also has a simplified conservative procedure, compared to DIN 2505, for flange analysis.
For leakage analysis AD-2000 refers to EN 1591.

3. DIN 2505
DIN 2505 does not have a procedure for a quantitative leakage analysis. DIN 2505 recommends the use of the joint diagram with the bolt and joint stiffnesses,deformations and loads.This will allow one to determine the requirde installation bolt preload and the remaining gasket preload when the joint is pressurized. If the preload is sufficient for the type of gasket the joint should be tight resp. not leak in an engineering sense, but one cannot determine the amount( mass or volume) of leakeage.
Leakage experts maintain that every bolted joint will leak a certain amount.
EN1591 allows the quantitive analysis of leakage.
I have not used EN1591. I have looked at it and it looks rather complicated to me.
I hope this answers your question otherwise don't hesitate to ask. These discussions are interesting
regards

Theo Schotten