Inspection and NDT For Process Piping

[Critzy416]

Good Afternoon,
I'm new to the forum and industry so if I miss something please forgive me. This topic didn't seem to be discussed in any of my previous findings.

I'm looking into what inspection practices are done in the process piping industry on welded joints. I’m familiar with ASME B31.3 specifying that minimum 5% of welds will be radiographed for each welder. We’ve had customers request higher inspection criteria, which is usually just based on bad experiences when low quality was an issue.

1) I wanted to find out what quantity of inspection the industry is practicing?

2)Also if certain processes or materials required a certain type of inspection procedure other than what’s stated in the code? If there was a rule of thumb? This didn’t seem to be mentioned in the code either; and as a welder prior to my degree, I have not encountered this topic.

Thank you

 

[weldstan]

Many of our Clients have requested 100% Visual examination of completed welds as well as the 5% RT for Normal Service. For low temp systems, manmy of our Clients request 100% RT and Visual inspection plus MT/PT of socket welds. I must say that there is no universal requirements of our Clients. PMI is also a normal requirement for alloy piping. I suggest that you get a copy of API 582 for further enlightenment.

 

[XL83NL]

The code (B31.3) specifies NDT percentages based on the applicable Fluid Services. These services, when they deviate from Normal fluid service, need to be designated by the user/owner (except for cat. D Fluid service, if I remember correctly). For cat. N(ormal fluid service), 5% is the minimum for circ joints. The exact requirements per weld type (circ, longi. Etc) however are governed in detail for each fluid service in the code. The code also has a table (341 dot something I think) which specifies what shall be evaluated for each type of NDT.

There's no requirement pertaining to certain materials (except for a specific Fluid services, like Elevated Fluid service) however, certain materials are typically used for specific services, e.g. sour service, corrosieve services, or high temperature services. Client requirements often address these services to code Fluid services, and from there, specify higher NDT percentages, sometimes even in extent of the code. They do this caus in the end, for B31.3, the owner has final responsibility for the piping design.

Industry practice as I know from my humble experience, is 5% RT for circ joints, 5% PT/MT for joints that cant be volumetrically evaluated (typically branch and fillet welds). This percentage is then often specifed per welder, per lot. The definition of lot is always important in this context. Make sure you have agreement on this with your customer/end user/owner.

 

[BigInch]

Similar requirements are made by B31.4 & B31.8. In addition the requirements may change according to the latest up to the minuite progressive testing results, ie. results and trends to the poorer side can increase the NDT requirements of sucessive constructions.

you must get smarter than the software you're using.