RTJ Gasket Seating Surface/TEMA Standard

[bmoorthy]

The TEMA standard has provided for acceptable levels of discontinuities/marks in the Gasket seating surface.

Can this be extended to U stamp jobs?

Can this (TEMA) acceptance be extended to the seating surface of RTJ type flanges?

If there is a Visually shallow indication/As welded (Un machined) portion in the flat/Horizontal portion of a RTJ type flange but the taper portion is in machined condition(My understanding is that taper portion is the gasket seating area) but Hydrotest is clear (that is no leak is observed) and All required NDTs are clear, is there scope for AI to still object to this situation.

 

[deanc]

Review SecVIII Div1 U-2(e),UG-90(b)(13),(c)(1)(k),UG-95,UG-96. What does your in-house standard say about surface finish? Do you have a flange standard or spec.? The AI may be making sure you are following your own requirements. Can you write a "system non-conformance" and Eng.disposition it to "use as is"?

 

[bmoorthy]

Our internal procedure does not address this situation. We may have to upgrade it to meet this kind of situation. Our system procedure says gasket seating surface shall have
surface finish as per the type of Gaskets and a Table of Surface finish is provided. Reference is Made to B 46.1 for measurement of Gasket seating surface finish.

As regards ASME clauses, it does not provide much teeth fo convincing AI.

Actually this is the full situation.

1) The flange is standard SA 182 F5/ANSI B 16.5/600 # flange, but the gasket seating and the inside surface were ouerlayed with 347. After the completion of welding the overlay all NDT conducted and cleared, the flange was welded to shell and heat treatment was completed. Before Hydro a small porosity was noticed (in the horizontal portion of RTJ joints porosity size 1mm), although it could have been left as it is, our over enthusiastic QC wanted explore/fill it. When an attempt was made to rectify, it turned out to be sub surface (long) slag. Hence it was decided to grind and then fill the same rather than leaving it as it is. On completion it was found to be too conspicuous. Being a heavey Heat exchanger and this being a nozzle, Machining of RTJ would pose further risk of Damage, hence went ahead with Hydro and found the hydro is clear.

Can we conclude that proof of Satisfactory gasket seating surface is passing the hydro.

Is the gasket seating surface of RTJ the taper portion or does it encompass the flat portion also.

Requesting for some back up info.

Thankyou

 

[deanc]

You must speak with the AI. Explain your reasoning.
If this is not acceptable refer to the NBIC for guidence
on a possible repair.