Valve sourcing goes international

Across many types of merchandise in quite so much of industries, the practice of combining assorted components from numerous resources around the world is the rule, not the exception. Should this be a priority for a management valve user? For instance, when an end consumer discovers that several parts are being made in China (Figure 1), should the consumer worry in regards to the quality?
When dealing with a serious valve vendor, the answer is “no.” There shouldn’t be any room for doubt when the seller has multiple checks and balances in place focusing on product high quality to ensure management valves operate as designed, need minimal maintenance, carry out safely and function within environmental rules.
Yet, regardless of such efforts by the seller, a control valve user might have questions about global sourcing and the country of origin. This article discusses how one main control valve vendor ensures product quality. Many other control valve distributors follow the identical or similar procedures.
Quality specification brings global assurance
Emerson enforces a complete quality specification for its Fisher management valves that have to be met by suppliers of pressure-containing and structural metal castings. The quality specification consists of 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 course of. The process completely investigates a possible supplier’s capacity to fulfill material specifications and relevant worldwide codes and requirements — in addition to particular necessities 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 should reveal a report of qualification by a third-party inspection company and conform to various standards, similar to ISO 9001:2000, ASME, A2LA, PED and others. It should pass a evaluation of its high quality program in addition to on-site audits of the foundry’s processes and procedures similar to welding, warmth treatment and non-destructive examination. Additional proof of performance is set by analysis of tryout castings to confirm specs are met.
Welding procedures — Welding is used in the course of the manufacturing and upgrading of castings, such as 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, every lot of weld filler should comply with ASME/AWS chemical analysis specifications. In Europe, compliance have to be to EN499. Weld filler will have to have actual chemistry.
Marking inspection and testing — Valve body castings have markings (Figure 2) that determine the foundry that poured the casting and that point out the warmth code. Material identification can additionally be sometimes shown on the physique casting, such as CC, CF8M, CN7M and others.
Casting checks — Emerson technicians conduct both visual inspections and mechanical checks on pressure-retaining castings.
As-cast external and internal surfaces are inspected visually for unacceptable irregularities, including scorching tears and cracks, shrink, sand inclusions, veining and rat tails. Mechanical testing includes a hydrostatic stress test to confirm the leak tightness of a control valve’s pressure-retaining components, together with the body and bonnet castings. The check process entails a fixture that closes off cavities that would be pressurized in service and then topics the component to the hydrostatic shell test stress applicable for the valve body materials and sophistication.
ASME B16.34 sets out the hydrostatic test pressure to make use of for steel and alloy valves. It’s calculated by multiplying the working stress by 1.5 and rounding to the subsequent higher 25 psig increment. Any visually detectable weeping or leaking through the stress boundary walls that are a part of the valve assembly is a compulsory cause for rejection (Figure 3).
Compliance with these specs must be ensured, in addition to with other necessities concerning supplies.
Figure 2. Markings identify the foundry and materials of the valve body. These management valve bodies have been cast at an Emerson-approved foundry in China.
Meeting materials requirements
Valve casting integrity and quality begins with specifications that call not just for premium materials, but also for the supplies that work best in the intended applications. These application requirements embody power and ductility as properly as resistance to sure elements, together with the make-up of the managed fluid, operating temperature and flow velocity.
For instance, chemical composition must be controlled exactly to realize an alloy’s meant efficiency stage. Carbon metal castings for valves supposed for use in oil and gasoline applications must meet NACE SP0472 recommendations that chemical composition be controlled to lower than 0.43% carbon equivalency. The decrease carbon content material improves weldability and reduces the potential for stress cracking by hydrogen sulfide sometimes found in oil and gasoline manufacturing and processing purposes.
Another example of materials tied to a selected software embody these for upstream oil and gasoline manufacturing. Many of these purposes occur in the arctic regions of Russia and Canada. For this service, castings are ASME SA 352 Grade LCC, whereas forgings should meet ASME SA 350 Grade LF2.
Many merchandise with global use now adjust to dual materials specs to fulfill ASME and European standards. For เกจวัดแรงดัน1บาร์ , steel castings are specified and licensed to both ASME SA216 Grade WCC and EN 10213 Grade 1.0619. Emerson often adds its own stringent requirements similar to the warmth treating of high nickel alloys, more demanding chemical composition or special welding procedures.
In the past, Emerson has supplemented standard ASTM and ASME specs to attain the improved corrosion-resistance ranges and excessive temperature capabilities supplied by high-nickel alloys. This is now completed by the new ASTM specification A990, which addresses each material composition and quality.
Figure three. Pressure-retaining elements of a valve are subjected to hydrostatic testing to judge the parts’ integrity. Visible leakage or seepage through a casting means computerized 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 tool. 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 by way of G, no cracking, sizzling 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 prepared, they’ll pose major issues, together with poor integrity, poor weldability and lower-than-expected corrosion resistance. A systematic foundry qualification process may be followed to avoid these casting difficulties.
The foundry should cast a 1-inch thick high-nickel take a look at plate (Figure 4) that meets ASTM Material Specification A990. It’s troublesome to forged because of 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 filled with a matching composition weld materials. The welder and procedure 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 reduce from the plate and bent over a 1½-inch mandrel per ASTM A990 into a U-shape.
เกจวัดแรงดัน250bar are examined closely for cracking along the weld heat-affected zone, casting grain boundaries or dendrite boundaries. Failure to satisfy quality standards will outcome within the disqualification of the foundry from further consideration. Casting patterns have to be devoted solely to high-nickel alloy service. Use of carbon steel or a stainless-steel sample is unacceptable as a result of variations in solidification properties.
Shrinkage charges for gates, risers and other equipment can vary considerably. Once the dedicated sample equipment for each of those components has been secured, try-out castings are poured for every pattern-alloy mixture. The castings are then radiographed.
The intent is to reveal any inherent casting defects — corresponding to shrinkage — that need to be eradicated by modifying the sample rigging.
Figure 4. In a foundry evaluation, a casting is full of weld filler, then sliced to yield a bar for bend testing.
A qualified foundry
Emerson has used a Chinese foundry (Figure 5) to solid Fisher valve our bodies for greater than a decade. After an exploratory go to by procurement and manufacturing specialists, followed by an intensive qualification process, the foundry was accredited and has been delivering high-quality valve physique and bonnet castings to Fisher valve manufacturing websites.
To assist guarantee the standard of the castings it produces, the Chinese foundry has carried out international requirements and has obtained certifications for German TUV and CE, Norway DNV, German Lloyd’s and American ABS, and has handed worldwide high 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 specifications for casting valve our bodies.
Control valve customers could be involved once they learn sure valve parts are not made in the us or Europe, but elsewhere. Perhaps their concern stems from expertise with different inferior products, corresponding to appliances, clothes or electronics made in those international locations and sold on-line. But if the valve components are being equipped to a major control valve vendor that has gone to nice lengths to qualify the foundry or provider, then customers could be assured the valves meet all specs.

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