Pressure Vessel Plate

Pressure Vessel Plate

 

You need to take care about your Pressure Vessel Plate Materials, there are lots of requirements and specific prohibitions in the ASME code.

 

Some of these requirements are ASME and Non ASME plate materials, plate specifications, inspection requirements and material test reports. This article describes these requirements for you.

 

What is ASME Material?

 

ASME Code Sec VIII DIV 1 requires the materials that are used for pressure containing parts to be one of:

 

 

Material specified in ASME section II materials but with some restrictions, which are stated in ASME Code Sec VIII Div 1 in subsection C e.g. UCS, UHF, UNF.

 

For example, SA 283 plate material is listed in ASME Sec II, but when you refer to subsection C in Sec VIII Div 1, you see it is not allowed to be used for lethal substance services as well as for unfired steam boilers. Also, you cannot use this material when you need your thickness to be greater than 5/8 inch.

 

 

What is Difference Between ASTM Material and ASME Material?

 

When you refer to ASME Section II Part A, you see all material with SA prefix identification and on one side there is an ASTM logo, and on the other side is ASME logo.

 

But the ASTM prefix is single A.

 

The material specification in ASME Section II Part A was originally developed by ASTM and then reviewed and adopted by ASME Code. That is the reason you see both societies' Logos.

 

For example, if you open the SA 516 material specification in ASME Section II, material Part A, edition 2004, you will see this statement below the page title:

 

“Identical with ASTM specification A 516/ A516M-90”;

 

This means you can use A 516 Edition 1990 instead SA 516 2004.

 

But if your ASTM material is A 516 and not manufactured based on ASTM Edition 1990, you cannot use this material unless you do the assessment based on clause UG-10 in ASME Section VIII Div 1, and your assessment result will determine either it is permissible, or you need to do more tests to recertify this material.

 

For some materials, the specifications are not identical or may be identical with some exceptions, so again we cannot use these ASTM material unless we make an assessment based on the above mentioned clause (UG-10)

 

Is it possible to use Non ASME material instead of ASME Section II material?

 

The answer is “Yes,” but with some conditions. These conditions ar addressed in UG-10(a) as following items:

 

Melting method, melting practice, deoxidation, quality and heat treatment to be same between suggested non-ASME material and equivalent permitted ASME section II material.

Material certificate proves there is no conflict in chemical analysis between suggested non-ASME material and equivalent permitted ASME material.

Material certificate proves the suggested non-ASME material was produced and tested in accordance to equivalent permitted ASME material.

The material certificate to be recertified by the equivalent permitted ASME material with a notation of “ Certified per UG-10”

Example:

 

A manufacturer received an order for manufacturing a pressure vessel with an SA 516 Gr.60 pressure vessel plate normalized material, but apparently this material is not available in the market...

 

So the material supplier recommended to the pressure vessel manufacturer to purchase an available P265GH material instead. The manufacturer requested a copy of the material certificate for P265GH to verify for recertification per UG-10.

 

Pressure Vessel Manufacturer Assessment:

 

Step 1: Checking of melting method, melting practices, deoxidation, and heat treatment

 

P265GH is produced based on the European EN-10028 Standard, manufacturer controls plate material certificate and confirms:

 

Melting method, practice, deoxidation and heat treatment are consistent with SA 516 Gr.60 specification, the current available P265GH material produced by basic oxygen process and secondary vacuum process refinement and both normalized.

 

Step 2: Plate material certificate prove there is no conflict in chemical analysis between the suggested non-ASME material and the equivalent permitted ASME material.

 

The manufacture controlled chemical analysis in pressure vessel plate material certificate of P265GH with SA 516 Gr.60 specification and confirm everything is in specific minimum or ranged limits.

 

Step 3: Plate material certificate prove the suggested non-ASME material produced and tested in accordance to equivalent permitted ASME material.

 

Manufacturer the first control with the required number of test specimens for each mechanical test, as well as the size of specimens and confirm that both standards are the same;

 

Then check the plate material mechanical test result for yield stress, tensile strength and elongation and confirm all are in specific range of SA 516 Gr.60.

 

Manufacturer control for plate material impact test requirement and notice impact test carried out by ISO V method and in - 53 degree F;

 

But SA 516 Gr.60 requires to be impact tested in -60 degree F with Charpy V-notch test method based on SA 370 Specification so there are two conflicts here. First is the test method, and seconder is in the test temperature.

 

So pressure vessel manufacturer requests that the plate material supplier provide a test plate and send the test piece to a laboratory for impact testing based the SA 516 Gr.60 specification.

 

The lab test report confirms that the P265GH plate material covers the SA 516 Gr.60 impact testing requirement.

 

Step 4: The material certificate is to be recertified by the equivalent permitted ASME material with a notation of “Certified per UG-10.”

 

The manufacturer purchases the P265GH plate material and changes the marking on the plate and also rectifies the material test report with SA 516 Gr.60 material. This material identification will be SA 516 Gr.60

 

In the above example, a vessel manufacturer with doing extra tests recertified a non ASME pressure vessel plate material.

 

In some other cases, this might not be possible even by extra testing for example if the tensile strength is less than the ASME permitted material.

 

Sometimes it might be recertified even without any extra test when everything falls in the limitation range of the ASME permitted material.

 

What is the Other Requirement for Pressure Vessel Plate?

 

UG-93 in ASME Code Sec VIII Div 1 specifies requirements for plate material inspection.

 

Based on this clause, only plate material is require to have a material test certificate(MTR).

 

It means this requirement only can be applied for plate material; for other material such as pipe and flange, MTR's are not required and marking on the materials would be acceptable.

 

You need to inspect the plate material per specification of ASME Sec II Part A. For example, for SA 516 Gr.60 refer to this specification and check the chemical composition, mechanical property with your MTR.

 

You need to check that the Heat Number stated in MTR is the same stenciled on the plate material marking and make sure this MTR belongs to this material.