SHELL material stanadard DEP 30.10.02.11.GEN, Thum Rule may be applied for deriving the impact properties if you have tested at -46 degree centigrade to derive at -20 or warmer temperatures, ( 1.5 JOULES PER DEGREE CENTIGRADE , Eg : 18 joules at -51 degree centigrade may be regarded as 27 joules at -45degree centigrade
Noramlly if it is tested at -46 degree centigrade there is no meaning asking for -20 degree or warmer ,Normally for NGL servcie etc -20degree or warmer impact is asked to take care of upset conditions such as sudden stop or shut downs etc to ensure the impact properties where material is not impact tested or not required by code.
For A333GR6 /A350 LF2 code calls for impact testing at -46 degree or cooler temeperatures and in Europe all materials need to be tested for +20 degree centigrade if ASME/API code does not specify.
Best Regards,
Francis Lobo
----- Original Message -----
From: Aarpee <ramprasad.chari@gmail.com>
To: Materials & Welding <materials-welding@googlegroups.com>
Sent: Mon, 25 Aug 2008 16:22:23 +0530 (IST)
Subject: [MW:1059] Impact testing at -29 deg c and warmer
Dear members,
As per PV code ASME SEC VIII Div 1,impact test is not mandatory for PV
materials for P 1 and Gr1 &2 materials upto thk of 1" for majority of
materials.However for high Pressure Natural Gas applications say 100
Bar design pressure,it is asked to do impact testing at -20 deg C for
materials like A333GR6/A350LF2CL1 materials.Inspite of having
satisfactory values at testing temperature of -45/-46 deg C,testing at
-20 deg C is insisted.Can anyone explain logic behind this?
Further,it may please be noted that as per:
UCS 66(c)-no impact testing is required for B16.5 flanges of ferritic
steel when used at MDMT not colder than -29deg C and;
UCS 66(d)-pipe size 4" and below(P NO 1),impact test exemption is
there as a function of Yield Stress for temp -104 Deg C and warmer
e.g. 20 ksi to 30 ksi-6.0mm thk.Which implies that for 6.0 mm thk pipe
of 4"NB and below,no impact test is mandatory for tempr upto -104 deg
C.
However for Natural Gas applications,for material like A106GR B/A105
materials,impact test at 0 deg C is insisted for sizes 2"NB and above.
Here again,can A106GR B/A105 materials be safely used without impact
testing upto -29 deg C?
Regards
Aarpee
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to materials-welding@googlegroups.com
To unsubscribe from this group, send email to materials-welding-unsubscribe@googlegroups.com
For more options, visit this group's bolg at http://materials-welding.blogspot.com/
The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.
-~----------~----~----~----~------~----~------~--~---
No comments:
Post a Comment