API 570 PREPARATOR PREPARATORY Y
TEASER 6: Case Study on Pre-heating and PWHT (Question)
Determine if pre-heating and PWHT is required in following cases and if required, provide minimum pre-heat temperature. If PWHT is required, provide minimum PWHT temperature, time and brinell hardness. There is no process related PWHT requirement. 1. A 106 Gr C pipes — NPS 12, Sch 80 2. A 106 Gr C pipes — NPS 12, Sch 160 Welding to be done when ambient temperature = (-5°C) 3. API 5L Grade x 60 pipes NPS 4, Sch 40 4. A 335 Grade P11 pipes NPS 10, Sch 80
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API 570 PREPARATORY
TEASER 6: Case Study on Pre-heating and PWHT (Answer) 1.
A 106 Gr C pipe belongs to P. No. 1. Pre-heat temperature = 50°F (Recommended) PWHT: (thk = 0.688”) — Not required
2.
Pre-heat temperature = 175°F (Required) PWHT: (thk = 1.312”) — PWHT is required. Temperature: 1100 – 1200°F Time: 1.312 hours (say, 80 mins.) Brinell hardness: Not mandatory
3.
Pre-heat = Pre-heat – 175°F (Recommended) PWHT: (thk = 0.237”) — Not required
4.
This pipe material belongs to P No. 4. Minimum pre-heating temperature = 300°F (Required) PWHT: (thk = 0.594”)— PWHT is required. Temperature: 1300 – 1375°F Time: 2 hours Brinell hardness: less than 225
P.O. Box No. 7274, Dammam 31462, Saudi Arabia
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TEL (966) 3 857 0006
[email protected] ● www.gotoITC.com
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FAX (966) 3 857 5255
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