After completed the Part 4: Pressure testing, we will continue to try on the Open/Close questions on Module ASME VIII – Impact test as a part of in-the-exam API 510 Body of knowledge (BOK)

If you don’t know how API 510 Certification scheme, See API 510 Certification Instructions

IMPACT TESTING
a) The inspector should be able to determine the minimum design metal temperature (MDMT) of a material which is exempt from impact testing (UG-20 (f), UCS-66, UCS-68(c).)

b) The inspector should understand impact testing requirements and impact testing procedure (UG-84)

Question 1: According to UG-20 (f) only. Is the below vessel exempted from Impact Test qualification.

Vessel Material  SA-516-70 normalized (plate) Thickness  2″, Min. Yield  38 KSI,  MDMT  -25 °F,  Coincident Ratio = 0.85

(a) YES, No need Impact Test for this product
(b) NO, Need to check further with UCS-66, and UCS-68(c)
(c) Depending on Client discretion
(d) None of above

Explanation: See UG-20(f), Our material applies to Curve D of Figure UCS-66 and exceeds the 1″ limit for exemption. It also exceeds and lower temperature limits – 20 °F.

Question 2: Following Question 1, according to UCS-66. Is the below vessel exempted from Impact Test qualification.

Vessel Material  SA-516-70 normalized (plate) Thickness  2″, Min. Yield  38 KSI,  MDMT  -25 °F,  Coincident Ratio = 0.85

(a) YES, No need Impact Test for this product
(b) NO,
(c) Should to be checked further with UCS-68(c)
(d) Both (b) & (c)

Explanation: Step 1: See Figure UCS – 66, Our material applies with thickness 2″, then the minimum temperature that exempt for impact test is initiated at – 4 °F. Step 2: See Figure UCS – 66.1, Using coincident ratio 0.85 found additional reduction in MDMT is -15*F, mean of -19*F in total.

Question 3: Following Question 2, according to UCS-68(c). Can we use addition PWHT to reduce the MDMT for exempting from impact Test qualification.

Vessel Material  SA-516-70 normalized (plate) Thickness  2″, Min. Yield  38 KSI,  MDMT  -25 °F,  Coincident Ratio = 0.85

(a) YES, After PWHT added – No need Impact test
(b) NO, The Impact test will be required
(c) Depending on Client discretion
(d) Either (a) or (b)

Explanation: See UCS-68 (c). If post weld heat treating is performed when it is not otherwise a requirement of this Division, a 30°F (17 °C) reduction in impact testing exemption temperature may be given to the minimum permissible temperature from Fig. UCS-66 for P-No.1 materials. P-1 materials (only) if post welded heat treatment is performed when it is not otherwise required. Be careful with UCS-56, the PWHT is mandatory by ASME VIII code for P-No.1 over 1.5″.

Question 4: A stationary vessel is made from 3 inch thick SA-516 Gr.70 plate that has been normalized. The MDMT is 30*F at 500 psig. Does this material require impact testing?

(a) No (Check Curve D)
(b) Yes
(c) Only if the vessel ID is less than 36 in
(d) Only if the vessel ID is greater than 36 in

Question 5: A vessel constructed of ‘curve B’ material is to be patch-plated with a fillet welded patch of the same material as the shell. The stress ratio is calculated as 0.64. The patch and vessel are 0.622 in thick with zero corrosion allowance. The MDMT is -15*F. From the information given, does the repair require impact testing of the repair procedure?

(a) Yes
(b) No (Stress ratio is considered as Alternative ratio in Figure 66.1)
(c) Yes, if optional PWHT is done
(d) There is insufficient information in the question to decide

Question 6: A 1.125 inch thick lap-welded patch is of SA-515 Gr 70 P-1 material. The vessel nameplate shows MDMT as 50*F with marking ‘HT’. The stress ratio is 1. From the information given, does the repair require impact testing of the repair procedure?

(a) Yes
(b) No (Name plate “HT” mean of PWHT, See UG-116)
(c) Yes, if optional PWHT is done
(d) There is insufficient information in the question to decide