Materials

Module from the Pressure Vessel Engineering Curriculum curriculum.

Module 3 - Materials for Pressure Vessels · Learning Objectives · 1. Select SA-516 Gr 70 with Normalizing requirement where appropriate · 2. Choose 1.25Cr-0.5Mo or 2.25Cr-1Mo for high-T hydrogen per API RP 941 Nelson Curves · 3. Specify SA-240 stainless grades (304L, 316L, 321, 347) for corrosion or high-T · 4. Apply MDMT and impact testing per UG-84 and UCS-66 / UCS-66.1 curves · 5. Identify when SA-516 requires PWHT (thickness > 1.5 in per UCS-56) · Common Pressure Vessel Materials

Spec	Grade	Max Temp (F)	Allowable 100F (ksi)	Allowable 700F (ksi)	Use
SA-516	Gr 55	900	15.7	13.6	Low-temp moderate vessel
SA-516	Gr 60	900	17.1	14.8	Standard CS
SA-516	Gr 70	900	20.0	17.3	Most common CS vessel
SA-106	Gr B (plate-equiv pipe)	800	20.0	17.3	Piping to 800 F
SA-387	Gr 11 Cl 2 (1.25Cr-0.5Mo)	1100	20.0	17.5	Reactor shells mid-T
SA-387	Gr 22 Cl 2 (2.25Cr-1Mo)	1100	20.0	18.9	Hydrotreater, H2
SA-240	TP304/304L	1500	20.0	16.2	Chemical, cryo
SA-240	TP316/316L	1500	20.0	16.8	Corrosion + T
SA-240	TP321/347 stabilized	1500	20.0	16.8	Above 800F SS
MDMT Rules Summary (UG-84 and UCS-66)
MDMT (Minimum Design Metal Temperature) = coldest metal temperature the vessel will see in service. Curves A, B, C, D in UCS-66 define whether impact testing is required. Curve B is typical for SA-516 Gr 70. Below MDMT curve, Charpy V-notch impact test required per UG-84: 15 ft-lb average, 12 ft-lb single minimum for CS < 0.394 in thick or 20 ft-lb average for thicker. MDMT reduction allowed per UCS-66.1 for lower operating stress (up to 125 F reduction if stress ratio < 0.35).

Source: Pressure_Vessel_Engineering_Curriculum_v1.xlsx · Sheet: Materials

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