Across many kinds of merchandise in a selection of industries, the apply of combining assorted elements from various assets around the globe is the rule, not the exception. Should this be a priority for a management valve user? For example, when an end user discovers that a number of elements are being made in China (Figure 1), should the person worry about the quality?

When dealing with a significant valve vendor, the reply is “no.” There shouldn’t be any room for doubt when the vendor has a number of checks and balances in place specializing in product quality to make sure management valves function as designed, want minimal upkeep, perform safely and operate within environmental regulations.
Yet, regardless of such efforts by the seller, a management valve user could have questions about world sourcing and the nation of origin. This article discusses how one major management valve vendor ensures product quality. Many different management valve distributors observe the identical or comparable procedures.
Quality specification brings international assurance

Emerson enforces a complete quality specification for its Fisher management valves that must be met by suppliers of pressure-containing and structural metallic castings. The high quality specification contains more than a dozen requirements that apply to the next areas:
Supplier qualification

Welding procedures

Marking inspection and testing

Tryout and sample castings

Production castings

Certification of compliance

Supplier qualification — Suppliers undergo a rigorous qualification process. The process completely investigates a potential supplier’s capacity to meet materials specs and relevant worldwide codes and standards — as properly as particular requirements associated to element manufacture. In the case of castings, a foundry is taken into account “qualified” when it passes a critical analysis by Fisher’s engineers.
The foundry must reveal a report of qualification by a third-party inspection agency and conform to varied requirements, corresponding to ISO 9001:2000, ASME, A2LA, PED and others. It must move a review of its high quality program in addition to on-site audits of the foundry’s processes and procedures such as welding, warmth therapy and non-destructive examination. Additional proof of performance is set by analysis of tryout castings to verify specifications are met.
Welding procedures — Welding is used through the manufacturing and upgrading of castings, corresponding to when radiographic examination is required. Welding requirements state that procedures and welder qualifications should meet ASME Section IX (or EN ISO 15614-1 and ISO 9606-1) qualification requirements. Similarly, each lot of weld filler must adjust to ASME/AWS chemical analysis specs. In Europe, compliance must be to EN499. Weld filler will need to have precise chemistry.
Marking inspection and testing — Valve body castings have markings (Figure 2) that establish the foundry that poured the casting and that point out the heat code. Material identification is also usually proven on the body casting, corresponding to CC, CF8M, CN7M and others.
Casting checks — Emerson technicians conduct both visible inspections and mechanical tests on pressure-retaining castings.
As-cast exterior and inside surfaces are inspected visually for unacceptable irregularities, together with scorching tears and cracks, shrink, sand inclusions, veining and rat tails. Mechanical testing entails a hydrostatic stress take a look at to confirm the leak tightness of a control valve’s pressure-retaining parts, together with the body and bonnet castings. The test procedure involves a fixture that closes off cavities that would be pressurized in service and then subjects the element to the hydrostatic shell take a look at stress appropriate for the valve body materials and class.
ASME B16.34 sets out the hydrostatic check stress to use for metal and alloy valves. It’s calculated by multiplying the working strain by 1.5 and rounding to the next higher 25 psig increment. Any visually detectable weeping or leaking by way of the pressure boundary partitions that are part of the valve meeting is a mandatory trigger for rejection (Figure 3).
Compliance with these specifications must be ensured, as nicely as with different necessities relating to materials.
Figure 2. Markings identify the foundry and supplies of the valve body. These control valve bodies were forged at an Emerson-approved foundry in China.
Meeting material requirements

Valve casting integrity and high quality begins with specs that decision not just for premium materials, but also for the supplies that work best within the supposed purposes. These software requirements embrace strength and ductility in addition to resistance to sure components, including the make-up of the managed fluid, working temperature and flow velocity.
For occasion, chemical composition must be managed exactly to realize an alloy’s intended performance level. Carbon steel castings for valves meant for use in oil and gas functions must meet NACE SP0472 recommendations that chemical composition be managed to lower than 0.43% carbon equivalency. เกจวัดแรงดัน improves weldability and reduces the potential for stress cracking by hydrogen sulfide usually present in oil and fuel production and processing applications.
เกจวัดแรงดัน of supplies tied to a particular utility embrace those for upstream oil and gasoline manufacturing. Many of those functions occur within the arctic areas of Russia and Canada. For this service, castings are ASME SA 352 Grade LCC, while forgings should meet ASME SA 350 Grade LF2.
Many products with world use now adjust to twin materials specs to fulfill ASME and European standards. For instance, steel castings are specified and licensed to each ASME SA216 Grade WCC and EN 10213 Grade 1.0619. Emerson usually adds its own stringent requirements similar to the heat treating of high nickel alloys, more demanding chemical composition or particular welding procedures.
In the past, Emerson has supplemented standard ASTM and ASME specifications to realize the enhanced corrosion-resistance ranges and high temperature capabilities provided by high-nickel alloys. This is now accomplished by the new ASTM specification A990, which addresses both materials composition and quality.
Figure 3. Pressure-retaining components of a valve are subjected to hydrostatic testing to evaluate the parts’ integrity. Visible leakage or seepage through a casting means computerized rejection.
Qualifying a foundry

As a part of a prospective foundry’s qualification, Emerson inspects and checks Fisher valve castings. Non-destructive testing radiography is used as a monitoring software. ASTM A990 Class C requires radiography of the primary casting of each pattern. The acceptance criterion is Level 3 for categories A, B and C. For classes D via G, no cracking, hot tears or inserts are allowed as specified in ASTM A990.
High-nickel alloy castings present improved performance in corrosive services and elevated temperatures. However, if high-nickel castings are improperly ready, they’ll pose major problems, including poor integrity, poor weldability and lower-than-expected corrosion resistance. A systematic foundry qualification course of could be followed to avoid these casting difficulties.
The foundry must cast a 1-inch thick high-nickel check plate (Figure 4) that meets ASTM Material Specification A990. It’s tough to forged because of the difference in cross-section between the base of the weld cavity (in the center) and the overall 1-inch thickness of the plate. The cavity of the poured plate is then full of an identical composition weld materials. The welder and procedure for this step must meet the standards outlined in Section IX of the ASME Boiler and Pressure Vessel Code. Test bars (3/8-inch thick) are cut from the plate and bent over a 1½-inch mandrel per ASTM A990 into a U-shape.
The bars are examined intently for cracking along the weld heat-affected zone, casting grain boundaries or dendrite boundaries. Failure to satisfy high quality standards will end result within the disqualification of the foundry from additional consideration. Casting patterns should be dedicated solely to high-nickel alloy service. Use of carbon steel or a stainless-steel pattern is unacceptable due to variations in solidification properties.
Shrinkage rates for gates, risers and different accessories can range considerably. Once the devoted sample tools for each of these parts has been secured, try-out castings are poured for each pattern-alloy mixture. The castings are then radiographed.
The intent is to reveal any inherent casting defects — such as shrinkage — that have to be eliminated by modifying the pattern rigging.
Figure four. In a foundry evaluation, a casting is filled with weld filler, then sliced to yield a bar for bend testing.
A certified foundry

Emerson has used a Chinese foundry (Figure 5) to solid Fisher valve bodies for greater than a decade. After an exploratory visit by procurement and manufacturing specialists, followed by an in depth qualification process, the foundry was approved and has been delivering high-quality valve body and bonnet castings to Fisher valve manufacturing websites.
To help guarantee the standard of the castings it produces, the Chinese foundry has applied international requirements and has obtained certifications for German TUV and CE, Norway DNV, German Lloyd’s and American ABS, and has passed worldwide quality system certifications of ISO 9001 and QS -9000.
The foundry has been awarded Gold Medals thrice consecutively within the Beijing International Casting, Forging and Industrial Boiler Expo. It has twice acquired an Excellent Supplier award from Emerson.
Figure 5. This Chinese foundry meets all specs for casting valve our bodies.
Summary

Control valve users may be concerned when they study certain valve parts usually are not made in the U.S. or Europe, but elsewhere. Perhaps their concern stems from experience with different inferior merchandise, corresponding to home equipment, garments or electronics made in these countries and offered on-line. But if the valve parts are being provided to a significant management valve vendor that has gone to nice lengths to qualify the foundry or provider, then customers may be assured the valves meet all specifications.
Share