Radiography of Castings

[lahane1443]

I have a very little knowledge in valves & castings, but I heard many times that RT is to be done 100% for 300# & above castings. is it true?? what this 100% means. is it for the entire body with Flanges or some crucial area only.
Can any body give the reference para in B 16.34 where the RT requirement is specified.
A quick reply is highly appreciated.

 

[Scotsinst]

100% usually refers to the quantity of valves RT'd. For example it is typical to RT 10% of CS valves CL600 but the same project could require 100% of SS valves CL900 and above to be RT'd. The percentage is of each valve size and type.
2" and below are normally DP tested because they're difficult to RT.

 

[9870204648]

lahane1443

As per ASME B16.34, Body, bonnet & cover of valves need to be radiographed.
for procedure and acceptance criteria read mandatory appendix1 of ASME B16.34-2004.

 

[reverman]

RT is not a mandatory requirement unless you are buying special class valves.

The RT in B16.34 covers only the critical areas of valve body and bonnets and is only mandatory when dealing with special class valves.

That said many manufactures do do voluntary RT on a sampling basis for standard class valves. You should contact the valve suppliers and ask them what their RT sampling procedure is for standard class valves.

Paragraph 8.3.1.1 of B16.34 details the RT requirements for special class valves.

 

[sk10009]

RT is supplementary requirement.
If you see the code(SA216,SA217,SA351),you can understandard.

 

[gerhardl]

Important: one side is what the ASME (or any relevant regulation says) the other side is the exact description of what the supplier requires.

Regrettably (and all over the world) specifications refer to for instance ASME without specifying exact what details and regulation paragraphs that is valid for the single case or type of valve, and how to apply the rules to the relevant situation, and how to and when for instance tests should be done and reacted to if something is wrong.

You are already on the right track in my opinion: sort out what is general information, and next step: ask for clarification from buyer/customer.

 

[HitokiriAoshi]

Hi,

I have just begin working for a valve manufacture in China who own our own foundry, assembly, and NDE (including RT) facilities. For the past 3 1/2 months I have been learning about as much as I can and I will share what i have learn here.

Though RT testing are not required per any production standard, many end-users opt-in RT testing for valves used in criticial applications such as dangerous medium, large NPS and/or high pressure class valve. (let's try and use pressure class instead of lb, one engineer at a time)

RT's are expensive tests that can drive up cost of production and delay delivery due detection of every last defect in the areas filmed; critical areas, and the valve manufactures often will repair the valves to pass RT testing whenever possible.

If RT is to be done, I personally recommend 100% sampling rate on the particular valve type.

In my opinion, 100% RT is overkill for class 300 valves unless used in absolutely critical application. PT, MT (magnetic valves only), and even UT will be sufficient.


-Sniper out

 

[reverman]

As a side note I would recommend you require RT shooting and reading be done by ASNT qualified personnel. Shooting can be done by a Level I but the person reading the film should be at least a Level II, However any foundry of reasonable size should have a Level III person on staff. This is especially important in China. The Chinese government issued RT qualification is not near as stringent as the ASNT qualifications.

The ASNT website has a database of all Level III qualified personnel so when reviewing ASNT certificates make sure that the person who signed the certificate is a valid ASNT level III qualified individual for RT. I have seen these documents faked before.

 

[HitokiriAoshi]

The best way to check is to ask for their level III's name.

Then go and search for them in the following link.

http://www.asnt.org/certification/cert/intro.cfm