Code question 5

[REGRUMBLE]

There is an article in section IX that indicates a PQR that has already been aproved with bend and tensile tests does not require these tests to be done again if you are only adding Impacts. I do not seem to be able to find the section. Anybody know what the number is.

 

[metengr]

REGRUMBLE;
You mean this......

QW-401.3 Supplementary Essential Variable
(Procedure). A change in a welding condition which will
affect the notch-toughness properties of a weldment (for
example, change in welding process, uphill or down vertical
welding, heat input, preheat or PWHT, etc.). Supplementary
essential variables are in addition to the essential
variables for each welding process.
When a procedure has been previously qualified to satisfy
all requirements other than notch toughness, it is then
necessary only to prepare an additional test coupon using
the same procedure with the same essential variables, but
additionally with all of the required supplementary essential
variables, with the coupon long enough to provide the
necessary notch-toughness specimens.
When a procedure has been previously qualified to satisfy
all requirements including notch toughness, but one
or more supplementary essential variable is changed, then
it is only necessary to prepare an additional test coupon
using the same welding procedure and the new supplementary
essential variable(s), with the coupon long enough
to provide the necessary notch-toughness specimens.

 

[Duwe6]

But it will look a little "odd" and will certainly catch an auditor's eye. I know a reputable lab that charges $300 for Tensiles & Bends. The anticipated problems wouldn't be worth the cost of these to me. Remember, WPS/PQR's are a Capital Expense -- good forever.

 

[Eddycurrentguy]

My experience has been that a PQR made for impact testing only is performed quite often. As long as the WPS is revised to include the new PQR [for impacts only], and the PQR references the appropriate WPS, you should not have any audit problems.

 

[weldtek]

Duwe6,
The practice of qualifying a WPS for impacts using one PQR for bends and tensiles and another PQR tested for impacts only, is absolutely legitimate.
It may look odd to you but I can assure you it is not uncommon. In fact, in following the rues of Sec IX, in certain cases, there is no way to cover the full range of thicknesses without qualifying multiple test plates of different thicknesses. If the fabricator elects to run bends and tensiles where not required by Code, that's their business, but, certainly an unnecessary expense.
As far as 'catching an auditors eye', any qualified auditor will understand and accept this practice.
Bear in mind, that my comments apply to the application of 'Code' rules not customer specs.

 

[gtaw]

The only problem I can see is that the WPS qualified without impacts typically do not include the welding parameters needed to calculate heat input which is listed as a supplementary essential variable.

This may not be a serious concern with plain carbon steels, but a procedure qualified using Q&T steels welded using one set of parameters can produce very different results when welded with different parameters.

Let's not forget what the letters ASME stand for.

Best regards - Al

 

[weldtek]

gtaw,
I would argue that it would be a serious concern for applications requiring impact tested plain carbon steels, however, the parameters that will govern an impact tested WPS are those recorded on the impact tested PQR, not those used for the non-impact tested PQR. This is a point that must be considered when qualifying a range of thicknesses with one plate.

 

[Duwe6]

Didn't say it wasn't "legal", just that it would catch an auditors eye. Thought of a further potential problem, Charpys are only valid if a close record of heat input -- travel speed/amps/volts -- and interpass temperature were kept. Those values have to be reflected in the final impact-qualified WPS.

 

[Guest102023]

Totally legal, but it relies on good records of welding parameters having been kept.

In the days when I roamed the shop floor, I learned to weld more plate length than needed, and then archive the offcuts, 'just in case'. Just in case the MDMT on next year's job was 10° lower, or a hardness or ferrite testing requirement popped up.

Because getting a busy foreman's attention for a money-losing proposition like weld procedure testing is something you like to minimize.

 

[Eddycurrentguy]

The only difference between the 'impact only' PQR and a standard PQR is the omission of tensile and bends. All other information required by Section IX will need to be on that document.

 

[REGRUMBLE]

Thanks to all for the inputs and all of the comments are valid. If we were only going to do this once then the added cost for bends and tesiles is not significant but when you need to do it for several different thickness and temperatures it can add up. Controling heat input is essential for impact values and therefore a separate PQR is needed for every thickness but the WPS can cover the range of values and thickness by code.