By David Diehl
Executive Technical Director of Training, Intergraph CADWorx & Analysis Solutions
There was an interesting presentation at the ASME B31.3 Process Piping meeting in April 2016. Some commonly-used piping components, within specification, are showing very low toughness. This low toughness results in brittle failure under ambient conditions. A summary of this presentation can be found at the Chemical Engineering July 2016 Letters to the Editor. If you use A106, A53, or API 5L pipe; A234 forgings; or A105 flanges, you should read the post.
This CAESAR II article is not focused on the important message provided in the B31.3 presentation but instead on the distribution of this information. Barry Messer of Fluor Corp. presented the material which combined studies by Fluor and the Material Testing Institute.
Of course, he was interested in informing the B31.3 committee about this dangerous situation and presenting their recommendations. But the main purpose of the B31.3 presentation was a search for a means to officially “alert” to the industry either by ASME or B31.3 regarding this problem.
B31.3 does not issue industry alerts. The options open to B31.3 are either a Code revision or a Code Case. These options were evaluated by the Materials subgroup (assisted by the Edit subgroup).
Because of the magnitude of the implied Code change (additional impact testing requirements for common materials), the materials subgroup had insufficient justification to support a Code change. (Note that because of processing time required for a Code change, this change would have a very low chance of making the 2016 edition of B31.3.)
A Code Case would better serve as a sort of “industry alert”. A Code Case is essentially an internal Request for Interpretation. Any person can request a formal interpretation of the Code, and formal interpretations are approved and published by the Committee at each (bi-annual) B31.3 meeting.
A Code Case is a request made by the Committee itself. In such a manner, the Committee can quickly publish “guidance” to address issues rather than waiting on the full balloting and publishing schedule of next Code edition. No such Code Case has been balloted by B31.3 to date.
One outcome of the B31.3 presentation is that a member of the Board on Pressure Technology Codes & Standards (BPTCS) agreed to add this topic to the summer Board meeting. Here again, no industry alert is forthcoming.
There is action in Section VIII. An active proposal there will further qualify “as forged” A105 flanges for cold service.
Additionally, construction code committees are aware of this issue and spreading the word. The Mechanical Contractors Association of America published the National Certified Pipe Welding Bureau (NCPWB) Technical Bulletin, Risk of Brittle Fracture of Carbon Steel Piping During Hydrostatic Testing.