b31.3 question

By leterburn (**)

Date 09-03-2011 02:08

Must be Braun........ where ya at? Minot to Montana here...... but on locations. DL

By jon20013 (*****)

Date 09-03-2011 03:49

Not going to discuss quality of current or past techs but B31.3 does have criteria for porosity by x-ray technique.

By Shane Feder (****)

Date 09-03-2011 06:32

GRB,
ASME B31.3 references ASME VIII Div 1 Appendix 4 for internal porosity.

(c) Maximum Size of Rounded Indication. (See Table
4-1 for examples.) The maximum permissible size of
any indication shall be 1⁄4t, or 5⁄32 in. (4 mm), whichever
is smaller; except that an isolated indication separated
from an adjacent indication by 1 in. (25 mm) or more
may be 1⁄3t, or 1⁄4 in. (6 mm), whichever is less. For
t greater than 2 in. (51 mm) the maximum permissible
size of an isolated indication shall be increased to 3⁄8
in. (10 mm).

It is more involved than just what I have posted above - Severe Cyclic and Normal Fluid Service have different acceptance criteria and also wall thickness plays a part,
Regards,
Shane

By GRB

Date 09-03-2011 12:19

thanks for the replies, figured there was a section, in 31 years this is the first time I've seen por. called on a 6010 downhill bead. We're over in Watord City now finishing up, headed to Killdeer shortly

By dbigkahunna (****)

Date 09-05-2011 00:00 Edited 09-05-2011 00:05

5P+ used to be really bad about leaving a GP at the start especially on tacks. If the start on a tack was not feathered, it would leave a GP at the start of the tack and when you came across it with the bead, it would not burn out. The GP would be about half the size of the root opening. And depending on the thickness of the pipe, it does not take much of a GP to get called. If you are welding on .375 pipe all you are allowed is a .09 gas pocket.
Dat aint much.
And if this just started happening, I would do a audit on the previous tech pictures to be sure he was not missing something or not calling it. At the same time look at the welding rods to see if there are issues with the bead rod.

By Shane Feder (****)

Date 09-05-2011 00:57

DBK,
What code have you quoted .375 and .09 from ? That seems to be more like API 1104 acceptance criteria - OP has noted B31.3.
As per ASME VIII Appendix 4 the maximum size of an individual pore is 1/4 t or 5/32" (4 mm) - whichever is smaller.
If it is an isolated indication it can be 1/3 t or 1/4" (6 mm) - whichever is smaller.
Those figures are for item D in Table 341.3.2 (Severe Cyclic conditions) - if it is Normal Fluid Service (which one would expect for compressor stations) the maximum size is further relaxed - 1.5 times item D if WT is greater than 6 mm.

So for NFS piping with 9.52 mm WT (.375) the maximum size of an isolated pore is
9.52 divided by 3 x 1.5 = 4.76 mm (that is a pretty big GP)
Regards,
Shane

By GRB

Date 09-13-2011 22:22

Once again , thanks for the replies, but I was correct and we have a new x-ray company