QW-403.6 OF ASME SEC. IX (MIN. THK. RANGE QUALIFICATION)

[CHINTUKUMAR GANDHI]

Dear Experts,   What shall be the minm. qualified thk. range if PQR is qualified with 6 mm. Nom. thk. with Notch toughness properties. Will it be 3 mm. or 6 mm. as per QW-403.6 of ASME Sec. IX?   Further, suppose If I shall qualify this procedure on 5 mm. thk. PQR test coupon (machined from 6 mm. thk.), which thickness shall I have to consider for temperature reduction during subsize test specimen testing? Will it be 5 mm.(actual thk.) or 6 mm. (nom. thk.)?   Awaiting your experts' opinion at the earliest.   Thanks & regards,     C. R. GANDHI

[John Henning]

Minimum thickness is 6mm.

 

QW-403.6 says “. . . where T is less than 6mm, the minimum thickness qualified is 1/2T . . .” .   Since your thickness is not less than the general rule of T to 2T applies.

 

Note this wording has also given me heart burn.  What I have done is to take a 1/4 inch plate (nominally 6mm) and have the thickness machined to 0.249 inches, this then qualifies for thickness 0.124 to 0.499 inches.  If I need the thickness I will also weld a 1/2 inch thick plate to qualify 1/2 to 1 inch. 

 

Enjoy.

 

John A. Henning

Welding & Materials

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[sevak hiren]

Dear Mr.Chintu,

 

I assume you can take 5 mm thk. specimen machined from 6 mm thk. plate, then the nominal thk. would be considered as 5 mm.

 

Qualified thk. with impact would be 2.5 mm to 10 mm.

 

Also you may consider 5 mm thickness for temperature reduction during subsize test specimen testing as per below clause.

 

UG-84(c)(3)

For material from which full size (10

mm

10 mm) specimens cannot be obtained, either due to the material shape or thickness, the specimens shall be either the largest possible standard subsize specimens obtainable

or specimens of full material nominal thickness which may be machined to remove surface irregularities.

[The test temperature criteria of (c)(5)(b) below shall apply for Table UCS-23 materials having a specified minimum tensile strength less than 95,000 psi (655 MPa) when the width along the notch is less than 80% of the material nominal thickness.]

Also please find below interpretation for your information.

Interpretation:                       

 

Question:         Does the following meet the intent of the Code?

                        The material is SA-516, Grade 70 where the actual plate thickness is 0.262 in. (6.56 mm) The minimum design temperature is -50°F and the Charpy impact specimen size is 10 x 5 mm.  Since the specimen width (0.197 in, 5.0 mm) is less than 80% of the actual plate thickness, what is the interpretation with regard to the appropriate test temperature per Table UG-84.2 and with regard to the applicable Charpy V-notch impact energy in foot-pounds per Table UG-84.1.

 

Reply:              The provisions of the second sentence of UG-84(c)(5)(b) require that the test temperature for the specimen in question is that which is adjusted by Table UG-84.2 for the temperature reduction corresponding to the actual material thickness and the temperature reduction corresponding to the Charpy specimen width actually tested.  In this case the test temperature would be reduced by the temperature reduction corresponding to the size of the specimen, 20°F, minus the temperature reduction corresponding to the material thickness, 10°F, resulting in a temperature reduction of 10°F below the minimum design temperature -50°F or a required test temperature of -60°F. The required energy in foot-pounds from Table UG-84.1 is multiplied by 5/10 or the ratio of the actual specimen width along the notch to the width of a full size specimen.

&

Full-size Charpy specimens are 10mm thick by 10mm wide. Sub-size Charpy specimens referred to in the following are defined as those of identical width but smaller thickness.

When relating sub-size Charpy results to full-size values, there are two issues of concern. One is the value of impact energy and the generally accepted method adopts a simple net section area-scaling rule to calculate impact energy values for thinner specimens. The second issue is the inherent shift (for identical material) in brittle-to-ductile transition for thinner ferritic steel.

Two relations have been developed to address this issue, based on the measured transition temperature shift for normalised Charpy energies between 25J/cm² and 50J/cm² (corresponding to 20J to 40J in full-size specimens).

The relations are given below:

ΔT1 = -0.7 (10-t)2	(Ref.1)
ΔT2 = 51.4 ln (2 (t/10)0.25 -1)	(Ref.2)

Both give similar results in thickness range between 2 and 10mm, see table below (T₂ is recommended in BS 7910).

Thickness, t mm	ΔT1, °C	ΔT2, °C
9	-1	-3
7.5	-4	-8
5	-18	-20
2.5	-39	-45

For Charpy requirements to be equivalent, the measured Charpy energy (normalised by the specimen net section area in J/cm ² units) has therefore to be specified at a colder temperature for sub-size specimens. The table below gives two examples using ΔT ₂.

	10 x 10mm specimens	5 x 10mm specimens	2.5 x 10mm specimens
Equivalent Charpy properties At temperature	27J (34J/cm2) -20°C	14J (34J/cm2) -40°C	7J (34J/cm2) -65°C
Equivalent Charpy properties At temperature	40J (50J/cm2) -20°C	20J (50J/cm2) -40°C	10J (50J/cm2) -65°C

[sevak hiren]

Further to my previous reply, please refer trail interpretation.

 

I assume you can 10 mm x 5 mm impact specimen from 5 mm base metal and conduct test at MDMT only.

 

Interpretation:                       

Subject:            Section VIII, Division 1, UG-84 and Table UG-84.2

 

Question 3:      For materials of thickness less than 0.394 in., and when the width along the notch is at least 80% of the plate material being tested, is the test temperature reduced below the minimum design temperature by an amount indicated in Table UG-84.2?

 

Reply 3:           We would refer you to the first sentence of UG-84(c)(5)(b) which indicates that the Charpy tests of such a specimen shall be conducted at a temperature not warmer than the minimum design temperature.  Further, there is no requirement for reducing this temperature further.

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[Zeghanu Gigi]

Dear John,

I saw your experience in welding field on WM site and I would like to ask you something:

I have to combine

1. PQR (Code ASME IX) -2"x5.54mm welded full GTAW 6G pos.-(Base metal ASTM A 106 Gr.B,Filler metal-ER 70 S3).

2. PQR (Code API 1104) -6"x 15.9mm welded full SMAW-6G pos.-(Base metal API 5L X52 ,Filler metal E 6010,Diam.3.2mm for root and cap,E 7010P1/G ,Diam.4mm for Fill.-API 1104.

It is possible?

 

GIGI ZEGHEANU

 

QA/QC /Welding  Dpt.

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[sevak hiren]

I assume you can not combine Section IX WPS & API 1104 WPS. (For both the standards , the requirements may be different)

[arung...@gmail.com]

Dear all,

I have a question:

We currently have a Welding Procedure Specification (WPS) and Procedure Qualification Record (PQR) for welding a 25mm plate using a combination of Gas Tungsten Arc Welding (GTAW) and Shielded Metal Arc Welding (SMAW), with impact testing conducted. The weld metal deposited by GTAW is 5mm, and SMAW is 20mm.

Now, if I only intend to use the SMAW process for welding 8mm and 15mm thick plates, both requiring impact testing, would our existing WPS still qualify for this welding scenario?

[venkateswara reddy Desireddy]

Your SMAW thick 20mm , lower limit is 16mm and higher limit 40mm. So your existing PQR not qualified.

D.V.reddy.

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[Kannayeram Gnanapandithan]

u can not. 403. 6 restrict on base metal thickness.  base metal thickness is 25mm which is 16mm to 50mm max. since u have done combination of process,  u cannot,  if u have done each single process,  then u can combine. weldmetal thickness is not creteria for impact, only base metal which affected by cooling rate which changes the Microstructure.  

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