Control valves are the workhorses of most processes. They touch the process fluids and often contend with many challenges—abrasive and corrosive fluids, high pressures and temperatures, and vibrations caused by piping and surrounding process equipment, to name a few.
In a Processing magazine article, Valve Sourcing Goes Global, Emerson’s Brant Pfantz highlights the many qualifications and practices suppliers must undertake for the control valves to meet the demanding requirements of their intended applications.
Brant opens by noting that users may have concerns about where the control valves are made. He shares Emerson’s approach in assuring control valve quality.
For Emerson, it:
…enforces a comprehensive quality specification for its Fisher control valves [hyperlink added by me] that must be met by suppliers of pressure-containing and structural metal castings. The quality specification includes more than a dozen requirements that apply to the following areas:
- Supplier qualification
- Welding procedures
- Marking inspection and testing
- Tryout and sample castings
- Production castings
- Certification of compliance
The foundry suppliers must pass a quality review with the Emerson team and:
…must demonstrate a record of qualification by a third-party inspection agency and conform to various standards, such as ISO 9001:2000, ASME, A2LA, PED and others.
From a welding procedures standpoint:
…procedures and welder qualifications must meet ASME Section IX (or EN ISO 15614-1 and ISO 9606-1) qualification standards.
The control valve bodies:
…have markings…that identify the foundry that poured the casting and that indicate the heat code. Material identification is also typically shown on the body casting, such as CC, CF8M, CN7M and others.
The Emerson team conducts visual inspections and mechanical tests, such as hydrostatic pressure testing on these castings, looking for:
…visually detectable weeping or leaking through the pressure boundary walls that are part of the valve assembly…
Materials used in casting are highly dependent on the application. For example, to avoid hydrogen sulfide stress cracks in oil & gas production applications:
Carbon steel castings for valves intended for use in oil and gas applications must meet NACE SP0472 recommendations that chemical composition be controlled to less than 0.43% carbon equivalency.
Read the article for more on the applicable standards, foundry qualifications, and quality practices to assure that you have right control valve to meet your application’s requirements. You can also connect and interact with other valve experts in the Valves, Actuators & Regulators group in the Emerson Exchange 365 community.