Valve sourcing goes global

Across many forms of products in a variety of industries, the follow of mixing assorted components from various assets around the globe is the rule, not the exception. Should this be a concern for a control valve user? For example, when an end consumer discovers that several parts are being made in China (Figure 1), ought to the user worry concerning the quality?
When coping with a significant valve vendor, the reply is “no.” There shouldn’t be any room for doubt when the seller has a number of checks and balances in place specializing in product quality to make sure management valves function as designed, need minimal upkeep, perform safely and operate within environmental regulations.
Yet, despite such efforts by the seller, a control valve consumer could have questions on global sourcing and the nation of origin. This article discusses how one major management valve vendor ensures product high quality. Many different control valve distributors follow the identical or comparable procedures.
Quality specification brings international assurance
Emerson enforces a comprehensive quality specification for its Fisher control valves that must be met by suppliers of pressure-containing and structural metallic 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 pattern castings
Production castings
Certification of compliance
Supplier qualification — Suppliers bear a rigorous qualification process. The course of totally investigates a potential supplier’s ability to meet materials specifications and relevant international codes and standards — as nicely as specific necessities related to element manufacture. In the case of castings, a foundry is considered “qualified” when it passes a critical evaluation by Fisher’s engineers.
The foundry should reveal a document of qualification by a third-party inspection company and conform to varied requirements, corresponding to ISO 9001:2000, ASME, A2LA, PED and others. It should move a review of its quality program as well as on-site audits of the foundry’s processes and procedures similar to welding, warmth therapy and non-destructive examination. Additional proof of performance is determined by analysis of tryout castings to verify specifications are met.
Welding procedures — Welding is used during the production and upgrading of castings, similar to when radiographic examination is required. Welding necessities 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 should comply with ASME/AWS chemical evaluation specs. In Europe, compliance must be to EN499. Weld filler should have actual chemistry.
Marking inspection and testing — Valve physique castings have markings (Figure 2) that determine the foundry that poured the casting and that indicate the heat code. Material identification can be typically shown on the body casting, such as CC, CF8M, CN7M and others.
Casting checks — Emerson technicians conduct each visual inspections and mechanical tests on pressure-retaining castings.
As-cast external and inner surfaces are inspected visually for unacceptable irregularities, including scorching tears and cracks, shrink, sand inclusions, veining and rat tails. Mechanical testing entails a hydrostatic stress check to substantiate the leak tightness of a control valve’s pressure-retaining elements, including the body and bonnet castings. The test procedure involves a fixture that closes off cavities that may be pressurized in service and then topics the element to the hydrostatic shell check stress applicable for the valve body materials and sophistication.
ASME B16.34 units out the hydrostatic check pressure to use for steel and alloy valves. It’s calculated by multiplying the working strain by 1.5 and rounding to the following larger 25 psig increment. Any visually detectable weeping or leaking via the strain boundary walls which are a half of the valve assembly is a compulsory trigger for rejection (Figure 3).
Compliance with these specifications must be ensured, in addition to with other requirements concerning materials.
Figure 2. Markings identify the foundry and materials of the valve body. These control valve our bodies have been cast at an Emerson-approved foundry in China.
Meeting material necessities
Valve casting integrity and quality begins with specifications that decision not only for premium materials, but additionally for the supplies that work finest in the supposed purposes. These software necessities include strength and ductility in addition to resistance to sure factors, including the makeup of the controlled fluid, working temperature and move velocity.
For instance, chemical composition should be managed exactly to attain an alloy’s intended performance level. Carbon steel castings for valves intended for use in oil and gas applications should meet NACE SP0472 recommendations that chemical composition be controlled to less than 0.43% carbon equivalency. The lower carbon content material improves weldability and reduces the potential for stress cracking by hydrogen sulfide sometimes found in oil and gasoline production and processing functions.
Another example of materials tied to a selected application embody these for upstream oil and gasoline production. Many of those functions occur in the arctic regions of Russia and Canada. For this service, castings are ASME SA 352 Grade LCC, whereas forgings must meet ASME SA 350 Grade LF2.
Many merchandise with global use now comply with dual material specs to meet ASME and European requirements. For instance, steel castings are specified and certified to both ASME SA216 Grade WCC and EN 10213 Grade 1.0619. Emerson often provides its personal stringent necessities corresponding to the heat treating of excessive nickel alloys, more demanding chemical composition or special welding procedures.
In the previous, Emerson has supplemented typical ASTM and ASME specs to achieve the improved corrosion-resistance levels and high temperature capabilities provided by high-nickel alloys. This is now accomplished by the brand new ASTM specification A990, which addresses each materials composition and quality.
Figure 3. Pressure-retaining parts of a valve are subjected to hydrostatic testing to judge the parts’ integrity. Visible leakage or seepage through a casting means automatic rejection.
Qualifying a foundry
As part of a potential foundry’s qualification, Emerson inspects and exams Fisher valve castings. Non-destructive testing radiography is used as a monitoring software. ASTM A990 Class C requires radiography of the first casting of each sample. The acceptance criterion is Level three for categories A, B and C. For classes D via G, no cracking, hot tears or inserts are allowed as laid out in ASTM A990.
High-nickel alloy castings provide improved performance in corrosive companies and elevated temperatures. However, if high-nickel castings are improperly ready, they will pose main issues, together with 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 solid a 1-inch thick high-nickel take a look at plate (Figure 4) that meets ASTM Material Specification A990. It’s difficult to forged due to the difference in cross-section between the base of the weld cavity (in the center) and the general 1-inch thickness of the plate. The cavity of the poured plate is then full of a matching composition weld materials. The welder and process for this step should meet the requirements outlined in Section IX of the ASME Boiler and Pressure Vessel Code. Test bars (3/8-inch thick) are minimize from the plate and bent over a 1½-inch mandrel per ASTM A990 right into a U-shape.
The bars are examined closely for cracking alongside the weld heat-affected zone, casting grain boundaries or dendrite boundaries. Failure to fulfill quality standards will end result in the disqualification of the foundry from further consideration. Casting patterns have to be devoted solely to high-nickel alloy service. Use of carbon metal or a stainless-steel sample is unacceptable due to differences in solidification properties.
Shrinkage rates for gates, risers and different accessories can vary significantly. Once the dedicated sample gear for every of these elements has been secured, try-out castings are poured for every pattern-alloy mixture. The castings are then radiographed.
The intent is to disclose any inherent casting defects — similar to shrinkage — that need to be eliminated by modifying the sample rigging.
Figure four. In a foundry analysis, a casting is filled with weld filler, then sliced to yield a bar for bend testing.
A qualified foundry
Emerson has used a Chinese foundry (Figure 5) to forged Fisher valve bodies for more than a decade. After an exploratory go to by procurement and manufacturing specialists, adopted by an intensive qualification process, the foundry was approved and has been delivering high-quality valve physique and bonnet castings to Fisher valve manufacturing websites.
To help guarantee the quality of the castings it produces, the Chinese foundry has carried out international standards 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 in the Beijing International Casting, Forging and Industrial Boiler Expo. It has twice obtained an Excellent Supplier award from Emerson.
Figure 5. This Chinese foundry meets all specs for casting valve our bodies.
เกจวัดแรงดัน could be involved when they study certain valve elements usually are not made in the U.S. or Europe, however elsewhere. Perhaps their concern stems from experience with other inferior products, corresponding to appliances, garments or electronics made in those countries and bought on-line. But if the valve components are being supplied to a major management valve vendor that has gone to nice lengths to qualify the foundry or provider, then users may be assured the valves meet all specifications.
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