Issues related to horizontal storage containers
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There is a horizontal storage vessel with a design pressure of 1.80 MPa, a design temperature of 50°C, an inner diameter of 1200 mm, and a volume of 5 m³. The shell is made of Q345R material, and the medium contained within is mixed liquefied petroleum gas. What category of pressure vessel should this vessel be classified as? What is the proportion of non-destructive testing for Class A and Class B welded joints? Is post-weld heat treatment necessary?
Refer to Annex A of the TSG R0004-2009 Regulations on Safety Inspection of Fixed Pressure Vessels for classification; refer to Articles 4 and 5 of HG20580-1998 Basic Provisions for the Design of Steel Chemical Vessels
Category 2 should involve 100% non-destructive testing; whether heat treatment is necessary depends on the hydrogen sulfide content in the liquefied gas – if there’s no such content, then heat treatment may not be required
Class II pressure vessels, non-destructive testing RT 20% III, post-weld heat treatment required
Should be Category II 100% inspection, heat treatment
For Category II containers, 100% non-destructive testing is required; heat treatment is necessary depending on the hydrogen sulfide content in the liquefied gas – it may not be needed if the content is low.
For Class II pressure vessels, 100% radiographic or ultrasonic testing is required for Class A and B welds. (Qualification level: Radiation Class III, Ultrasound Class II) Post-weld heat treatment is required.
It belongs to category II containers； A, B: 100% radiographic or ultrasonic inspection; acceptable quality level: Grade 3 for radiography, Grade 2 for ultrasonic inspection ； Heat treatment must be carried out after welding.
1. This vessel shall be classified as a Class II pressure vessel. 2. The non-destructive testing ratio for Class A and B welded joints is 100% RT. 3. Post-weld heat treatment is required
100% flaw detection rate required for Class II and Class AB joints; post-weld heat treatment is necessary