Valve sourcing goes world

Across many types of products in a variety of industries, the apply of mixing assorted elements from numerous assets all over the world is the rule, not the exception. Should this be a priority for a management valve user? For example, when an end user discovers that several parts are being made in China (Figure 1), should the person worry concerning the quality?

When coping with a serious valve vendor, the reply is “no.” There shouldn’t be any room for doubt when the seller has a quantity of checks and balances in place focusing on product high quality to ensure control valves function as designed, need minimal upkeep, perform safely and function inside environmental regulations.
Yet, regardless of such efforts by the seller, a management valve person could have questions about international sourcing and the country of origin. This article discusses how one major management valve vendor ensures product quality. Many different management valve vendors comply with the identical or comparable procedures.
Quality specification brings world assurance

Emerson enforces a complete high quality specification for its Fisher control valves that must be met by suppliers of pressure-containing and structural metallic castings. The high quality specification includes more than a dozen necessities that apply to the following 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 course of thoroughly investigates a possible supplier’s capability to meet material specs and relevant worldwide codes and requirements — as well as specific requirements associated to element manufacture. In the case of castings, a foundry is taken into account “qualified” when it passes a important evaluation by Fisher’s engineers.
The foundry must show a report of qualification by a third-party inspection company and conform to numerous requirements, corresponding to ISO 9001:2000, ASME, A2LA, PED and others. It must pass a evaluate of its high quality program in addition to on-site audits of the foundry’s processes and procedures similar to welding, heat 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, similar to when radiographic examination is required. Welding necessities state that procedures and welder qualifications must meet ASME Section IX (or EN ISO 15614-1 and ISO 9606-1) qualification standards. Similarly, each lot of weld filler must adjust to ASME/AWS chemical analysis specs. In Europe, compliance must be to EN499. Weld filler must have precise chemistry.
Marking inspection and testing — Valve physique castings have markings (Figure 2) that identify the foundry that poured the casting and that point out the heat code. Material identification can additionally be usually shown on the physique casting, similar to CC, CF8M, CN7M and others.
Casting checks — Emerson technicians conduct each visible inspections and mechanical checks on pressure-retaining castings.
As-cast external and inside surfaces are inspected visually for unacceptable irregularities, together with hot tears and cracks, shrink, sand inclusions, veining and rat tails. Mechanical testing includes a hydrostatic stress take a look at to substantiate the leak tightness of a control valve’s pressure-retaining components, including the physique and bonnet castings. The take a look at process includes a fixture that closes off cavities that might be pressurized in service after which topics the part to the hydrostatic shell check strain appropriate for the valve body materials and sophistication.
ASME B16.34 sets out the hydrostatic take a look at pressure to make use of 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 stress boundary partitions which are part of the valve assembly is a compulsory cause for rejection (Figure 3).
Compliance with these specifications should be ensured, in addition to with other requirements concerning supplies.
Figure 2. Markings identify the foundry and materials of the valve body. These management valve our bodies had been cast at an Emerson-approved foundry in China.
Meeting material requirements

Valve casting integrity and high quality begins with specs that call not only for premium materials, but additionally for the materials that work finest within the supposed functions. These software requirements embrace power and ductility in addition to resistance to certain factors, including the makeup of the managed fluid, working temperature and flow velocity.
For occasion, chemical composition must be managed exactly to attain an alloy’s meant performance level. Carbon metal castings for valves supposed to be used in oil and fuel purposes should meet NACE SP0472 recommendations that chemical composition be managed to less than 0.43% carbon equivalency. The decrease carbon content material improves weldability and reduces the potential for stress cracking by hydrogen sulfide usually found in oil and gasoline manufacturing and processing applications.
Another example of materials tied to a particular utility embody those for upstream oil and gasoline manufacturing. Many of those purposes occur in the arctic areas of Russia and Canada. For this service, castings are ASME SA 352 Grade LCC, whereas forgings must meet ASME SA 350 Grade LF2.
Many products with world use now adjust to dual material specs to meet ASME and European requirements. For example, metal castings are specified and authorized to each ASME SA216 Grade WCC and EN 10213 Grade 1.0619. Emerson often adds its own stringent necessities similar to the warmth treating of excessive nickel alloys, extra demanding chemical composition or particular welding procedures.
In the previous, Emerson has supplemented typical ASTM and ASME specifications to attain the enhanced corrosion-resistance levels and excessive temperature capabilities supplied by high-nickel alloys. เกจวัดอาร์กอน is now achieved by the model new ASTM specification A990, which addresses both material composition and quality.
Figure 3. Pressure-retaining components of a valve are subjected to hydrostatic testing to gauge the parts’ integrity. Visible leakage or seepage through a casting means computerized rejection.
Qualifying a foundry

As part of a prospective foundry’s qualification, Emerson inspects and tests Fisher valve castings. Non-destructive testing radiography is used as a monitoring software. ASTM A990 Class C requires radiography of the first casting of every pattern. The acceptance criterion is Level 3 for classes A, B and C. For classes D via G, no cracking, sizzling tears or inserts are allowed as specified in ASTM A990.
High-nickel alloy castings provide improved performance in corrosive services and elevated temperatures. However, if high-nickel castings are improperly ready, they’ll pose main issues, including poor integrity, poor weldability and lower-than-expected corrosion resistance. A systematic foundry qualification process can be followed to keep away from these casting difficulties.
The foundry must solid a 1-inch thick high-nickel check plate (Figure 4) that meets ASTM Material Specification A990. It’s troublesome to forged due to the distinction 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 filled with an identical 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 requirements will outcome within the disqualification of the foundry from additional consideration. Casting patterns have to be devoted solely to high-nickel alloy service. Use of carbon steel or a stainless-steel pattern is unacceptable as a outcome of variations in solidification properties.
Shrinkage rates for gates, risers and different accessories can differ significantly. Once the dedicated sample equipment for every of those components has been secured, try-out castings are poured for every pattern-alloy combination. The castings are then radiographed.
The intent is to reveal any inherent casting defects — similar to shrinkage — that need to be eradicated 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 cast Fisher valve bodies for greater than a decade. After an exploratory go to by procurement and manufacturing specialists, adopted 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 assist guarantee the quality of the castings it produces, the Chinese foundry has implemented international standards and has obtained certifications for German TUV and CE, Norway DNV, German Lloyd’s and American ABS, and has handed worldwide quality system certifications of ISO 9001 and QS -9000.
The foundry has been awarded Gold Medals three times consecutively in the Beijing International Casting, Forging and Industrial Boiler Expo. It has twice received an Excellent Supplier award from Emerson.
Figure 5. This Chinese foundry meets all specs for casting valve bodies.
Summary

Control valve customers could be involved once they be taught certain valve parts aren’t made in the united states or Europe, but elsewhere. Perhaps their concern stems from experience with other inferior products, such as home equipment, garments or electronics made in those international locations and bought on-line. But if the valve components are being provided to a serious control valve vendor that has gone to great lengths to qualify the foundry or supplier, then users may be assured the valves meet all specs.
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