Non Ferrous in Low Pressure Designs

[MangaMech]

I am looking for advice regarding aluminum flow hardware such as simple valves, strainer housings and diverters (swept shapes with multiple outlets and flanges) in low pressure <150PSI fuel oil applications i.e. for diesel and kerosene.

I see these materials used in road tanker flow 'jewelery' and in LPG meters etc but have been unable to locate a 'hard' code for guidance. I would appreciate assistance in getting my head around the following.

Regardless of material what benchmark standards guide material selection, design or qualification?

In design when is a valve not a pressure vessel?

Are there US or international standards/codes that can be applied from the ferrous materials into lightweight non ferrous?

Is there a common sense or good engineering practice approach that gives sound design for acceptance by end users and regulatory bodies?

When does it become an imperative to move away from lightweight and low cost alloys?


thanks in advance

 

[metengr]

This is a difficult question to answer. I would say that the use of ferrous or non-ferrous material will be mandated by the applicable code or standard. For example- at a high level you have the Code of Federal Regulations that mandate specific use of materials, or you have the Department of Transportation (DOT), that regulates , design, materials, fabrication and inspection of propane or fuel trucks, and you have the NFPA for fuel delivery systems.

Drilling down to the State level you have state agencies that mandate rules and regulations for use of materials, in areas like boilers and pressure vessels, piping , etc and have incorporated many ASME/ANSI Standards. Regarding valves, the answer to your question depends again on the specific application. Certain valves can be repaired under ASME/ANSI standards, which kick you back into ASME Boiler and Pressure Vessel Code, Section VIII, Div 1 (treated as an unfired pressure vessel). Other valves may fall under a different standard for selection and repair.

The numerous Codes and Standards that are developed are normally consensus based with input from many subject matter experts. First and foremost is safety. In most cases, the codes or standards committees will not endorse one material over another for a specific application. They will provide recommendations regarding material limitations based on loss of strength, ductility or corrosion/degradation under various temperature and pressure service conditions .

The final selection of a material rests with the designer using technical guidance from the applicable code or standard. Optimum use of materials are not addressed in Codes or Standards.