Per B31.3 Impact test exemption of weld metal below -29°C (-20 F) 1

[Santiago Vacca]

Dear Colleagues,

We are defining the welding of a B31.3 piping system intendeg for LPG, the MDMT required is defined as -40°C.

Base materials are Curve B or 29°C per Table A-1.
The minimum temperature without impact for base metals is further reduced to -48°C by Para. 323.2.2(h) as Stress ratio is 0.5. Then base metals are impact exempted.

What should be the case for welds under this situation?

There is an ASME interpretation as follows:

Question:
In accordance with B31.3-2020 edition paragraph 323.2.2, Table 323.2.2 and Table 323.3.1, is impact testing of the heat affected zone (HAZ) in accordance with Table 323.3.1 Box 6 required for minimum design temperatures of -18°C (0°F) through -29°C ( -20°F) when both the weld metal and the base materials are exempt from impact testing in accordance with Table 323.2.2 Box A-3 and para. 323.2.2?
Reply:
No.

But our case has a minimum design temperature below -29°C.

323.2.2(h) further states that:
For carbon, low alloy, and intermediate alloy steel welds that require impact testing in accordance with Table 323.2.2, Box A - 3 ( b ) , the temperature reduction from Figure 323.2.2B shall be applied to -29° C (-20° F).

Also Figure 323.2.2A note(5) states: A welding procedure for the manufacture of pipe or components shall include impact testing of welds and HAZ for any design minimum temperature below -29° C (-20° F), except as provided in Table 323.2.2, A-3(b).

The intent is to use 7018-1 electrode with non impact wps, as this electrode is clasified by impact at -45°C.

I also read the B31T, fom this standard I interpret that under -29°C WPS is with impact.

Thank you all in advance.

 

[GD2]

Santiago Vacca,

I don't have 202o edition of B31.3. I don't see 323.2.2 (h) in my 2016 edition.

Did you calculate the stress ratio? While it is easy to calculate the stress ratio per Notes (a)(1) and (a)(2) of Fig. 323.2.2B, you might need the help of a stress analyst to calculate (1)(3).

First fix the MDMT based on Fig 323.2.2A and Fig 323.2.2B with notes on stress ratio. if your calculated stress ratio is above 0.3, the MDMT will be limited to -48C. With 0.3 or below, it will be limited to -104C.

With the calculated MDMT, go to Table 323.2.2 and interpret box A-3(b).

GDD
Canada

 

[r6155]

Must work with current edition B31.3 2022

Regards

 

[XL83NL]

Must work with current edition B31.3 2022

Technically, that’s incorrect - by one day. Your post becomes valid tomorrow (first of August).

Refer to the third page of the 2022 edt., which (similar to all previous editions) states that the edition under consideration becomes effective 6 months after issuance. Date of issue was 31st of Jan.

Huub
- You never get what you expect, you only get what you inspect.

 

[r6155]

Hi XL83NL, please see the following
ASME B31.3 2022
INTRODUCTION
This edition of Code Section B31.3 is not retroactive.
Normally, agreement is made between contracting
parties to use a specific edition, considering requirements
of the authority having jurisdiction. When specified as the
latest edition and when no edition is specified, the specific
edition is the one issued at least 6 months prior to the
original contract date for the first design activity.



Also, as information, see ASME VIII Div 1
MANDATORY APPENDIX 43
ESTABLISHING GOVERNING CODE EDITIONS AND CASES FOR
PRESSURE VESSELS AND PARTS

43-1 GENERAL
(a) After Code revisions are approved by ASME, they
may be used beginning with the date of issuance shown
on the Code. Except as noted in (b) below, revisions be
come mandatory 6 months after the date of issuance.
Code Cases are permissible and may be used beginning
with the date of approval by ASME. Only Code Cases that
are specifically identified as being applicable to this Sec-
tion may be used. At the time a Code Case is applied, only
the latest revision may be used. Code Cases that have
been incorporated into this Section or have been annulled
shall not be used.

Regards

 

[XL83NL]

Yeah. But what’s your point? I’m not seeing anything new as to what I said. Sure the code is not intended to be retroactive but that’s not the case or point of discussion here.

In fact the OP referred to the 2020 edt., soccer might assume he needs to work to that edition.

You can by the way leave ASME VIII out of the discussion as were taking B31.3 piping here.

Huub
- You never get what you expect, you only get what you inspect.

 

[Santiago Vacca]

Dear coallegues,

There are no changes in these paragraphs in B31.3 ed. 2020 and 2022.

Stress ratio is about 0.5 so curve B materiales, after Fig. 323.2.2B, fall below the design minimum temperature(DMT=-40°C).
But is the reducton limit -48°C or -29°C?

323.2.2 (h) states:
For carbon, low alloy, and intermediate alloy steel
materials (including welds) that have not been qualified
by impact testing, the minimum temperature from
Table A-1, Table A-lM, or Figure 323.2.2A may be
reduced to a temperature no c o l d e r than -48 ° C
(-55 ° F) by the temperature reduction provided in
Figure 323.2.2B when (c) applies. For carbon, low
alloy, and intermediate alloy steel welds that require
impact testing in accordance with Table 323.2.2, Box
A - 3 ( b ) , the temperature reduction from Figure
323.2.2B shall be applied to -29° C (-20° F).

The end of this paragrath confuses me. Box A - 3 ( b ) states that:

A-3 (b) The weld metal of the
welding procedure qualification
test coupon shall be impact
tested at or below the design
minimum temperature when
that temperature is less than
-18° C (0° F), except when
Note (3) or Note (4) is satisfied;
testing of the weld metal
is not required when the clas-
sification of the welding
consumables according to the
filler metal specification
requires impact testing
below the design minimum
temperature.

This means I can only apply the temperature reduction from Figure 323.2.28 down to -29°C? So base metals requiere impact too? I don´t think so.

could it be the case that when impact tested wps is used, base metals could be reduced down to -48°C, but when wps is not impact tested base metal reduction is only down to -29°C. This is logical since the HAZ is tested for toughness in the first situation but not in the second.


I read both B31.3 and B31T. B31T is clear and for this situation base mateal es expempt of impact, WPS needs to be with impact test when DMT is below -29°C.
And lots of weld consumables require impact testing unless it is a SFA consumable certified by immpact below DMT. As is the case for 7018-1.

Thank you all in advance.

 

[david339933]

323.2.2(h) allows you to lower the MDMT to -48C for the weldment. You cannot go colder even though the coincident ratio may result in a lower temperature.
You start at -29C and apply the temperature reduction of the ratio for the weld metal.
You can only use this when all of 323.2.2(c) are applicable.

 

[GD2]

Santiago Vara,

Let's start all over. You stated the following:

[ul]
[li]Process MDMT (design minimum temp as per code language) =-40 C.[/li]
[li]Material = fits Curve B. What is the material and wall thickness?[/li]
[li]Stress ratio: 0.5[/li]
[/ul]

Note (3) of Table 323.2.2 is very critical to understand because this is single note that will essentially determine requirement of impact testing in Box A-3(b). Note (4) is pretty simple to understand.

Can you provide the temperature (minimum temperature as per code language) you have obtained from Fig 323.2.2A?

GDD
Canada

 

[WE91]

Scenario that may clear it up.

MDMT= -40F

Pipe- A333 6 = impact exempt per table A-1 to -50F

Consumable - 7018-1 pre use impact tested in accordance with SFA 5.1

Impacts are not required for piping or WPS.