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**IMPACT TESTING**

The inspector should be able to:

a) Determine the minimum metal temperature of a material (MDMT), which is **exempt from impact** testing (ASME B31.3, Section 323.2.2, Figure 323.2.2A & Table A-1).

b) Determine the minimum required **Charpy V-notch impact values** of a given material. (ASME B31.3, Section 323.3, Table 323.3.5)

Question 1: What is the minimum design temperature for a pipe made in A516 Gr55 containing liquid petroleum gas at 150 psig that is 30 mm thick?

(a) 0°C

(b) -10°C

(c) -15°C

(d) -20°C

Answer: C, B31.3: minimum design temperatures, B31.3 graph 323.3.2A. Curve C at 30 mm thick shows **–15°C**

Question 2: If the material has a design **stress** of 160 psig and the internal pressure that produces a **stress** of 64 psig, what **reduction** can be made in the minimum design temperature without impact testing the material?

(a) 20°C

(b) 40°C

(c) 60°C

(d) 80°C

Answer: C, B31.3 graph 323.3.2B. Stress ratio = 64/160 = **0.4** gives a temperature** reduction **of** 60°C**

Question 3: What is the minimum value of Charpy impact required for steel made of fully deoxidized API 5L Gr. B pipe?

(a) 18 joules

(b) 14 joules

(c) 10 joules

(d) 7 joules

Answer: B, B31.3 section 323.3.5. **Checking strength** from B31.3 table A-1 gives 60 ksi. Looking in table 323.3.5 for 65 ksi and less gives a **minimum Charpy value **of 14 J.

Question 4: An **A 381** Y-35 pipe is **1.0” thick** and is installed in a system operating at 150 psi. A replacement pipe will be ordered, and will be the same material (**not** normalized or quenched/tempered). If the design minimum temperature is 400°F and the nominal pressure **stress is 10,000 psi** (10 ksi), what temperature can this material be operated at without impact testing?

a. +7° F

b. -7° F

c. 68° F

d. 61° F

Answer: A, From Fig.323.2.2A, Not-normalized A 381 will be still used by **curve A** as indicated in Table A-1.

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