UG-84(c)(3)
For material from which full size (10mm
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 obtainableor 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 | 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 | 5 x 10mm | 2.5 x 10mm |
| Equivalent | 27J | 14J | 7J |
| Equivalent | 40J | 20J | 10J |
On Thu, Jun 7, 2012 at 7:49 PM, John Henning <jhenning@deltak.com> wrote:
--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
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of CHINTUKUMAR GANDHI
Sent: Wednesday, June 06, 2012 5:30 AM
To: materials-welding@googlegroups.com
Subject: [MW:14478] QW-403.6 OF ASME SEC. IX (MIN. THK. RANGE QUALIFICATION)
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
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