Across many forms of merchandise in quite so much of industries, the follow of combining assorted components from various sources around the world is the rule, not the exception. Should this be a concern for a management valve user? For instance, when an end user discovers that a quantity of components are being made in China (Figure 1), should the person fear concerning the quality?
When dealing with a serious valve vendor, the reply is “no.” There shouldn’t be any room for doubt when the seller has multiple checks and balances in place specializing in product quality to make sure control valves function as designed, need minimal upkeep, carry out safely and operate within environmental rules.
Yet, despite such efforts by the seller, a management valve person may have questions about world sourcing and the nation of origin. This article discusses how one major control valve vendor ensures product quality. Many different management valve distributors observe the same or related procedures.
Quality specification brings world assurance
Emerson enforces a comprehensive high quality specification for its Fisher control valves that should be met by suppliers of pressure-containing and structural metal castings. The quality specification includes greater than a dozen necessities that apply to the next areas:
Supplier qualification
Welding procedures
Marking inspection and testing
Tryout and pattern castings
Production castings
Certification of compliance
Supplier qualification — Suppliers undergo a rigorous qualification process. The course of thoroughly investigates a possible supplier’s ability to satisfy material specs and relevant international codes and standards — as properly as particular necessities related to part manufacture. In the case of castings, a foundry is considered “qualified” when it passes a important analysis by Fisher’s engineers.
The foundry should reveal a record of qualification by a third-party inspection agency and conform to numerous standards, similar to ISO 9001:2000, ASME, A2LA, PED and others. It should move a review of its quality program in addition to on-site audits of the foundry’s processes and procedures such as welding, heat remedy and non-destructive examination. Additional proof of efficiency is determined by analysis of tryout castings to confirm specs are met.
Welding procedures — Welding is used during the production and upgrading of castings, corresponding 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 standards. Similarly, each lot of weld filler must adjust to ASME/AWS chemical evaluation specs. In Europe, compliance have to be to EN499. Weld filler should have precise chemistry.
Marking inspection and testing — Valve body castings have markings (Figure 2) that identify the foundry that poured the casting and that indicate the heat code. Material identification is also usually shown on the body casting, corresponding to CC, CF8M, CN7M and others.
Casting checks — Emerson technicians conduct both visual inspections and mechanical tests on pressure-retaining castings.
As-cast external and inside surfaces are inspected visually for unacceptable irregularities, including sizzling tears and cracks, shrink, sand inclusions, veining and rat tails. Mechanical testing includes a hydrostatic pressure check to confirm the leak tightness of a management valve’s pressure-retaining elements, including the physique and bonnet castings. The take a look at process entails a fixture that closes off cavities that may be pressurized in service after which subjects the element to the hydrostatic shell check pressure appropriate for the valve body material and sophistication.
ASME B16.34 sets out the hydrostatic test strain to use for metal and alloy valves. It’s calculated by multiplying the working pressure by 1.5 and rounding to the following larger 25 psig increment. Any visually detectable weeping or leaking via the strain boundary walls that are part of the valve assembly is a mandatory trigger for rejection (Figure 3).
Compliance with these specifications have to be ensured, in addition to with different necessities relating to materials.
Figure 2. Markings identify the foundry and materials of the valve body. These management valve bodies have been forged at an Emerson-approved foundry in China.
Meeting materials necessities
Valve casting integrity and quality begins with specifications that call not only for premium materials, but additionally for the materials that work best in the supposed applications. These application requirements embrace power and ductility in addition to resistance to sure factors, together with the make-up of the managed fluid, working temperature and move velocity.
For instance, chemical composition should be managed precisely to achieve an alloy’s meant efficiency level. Carbon metal castings for valves meant for use in oil and gas functions should meet NACE SP0472 recommendations that chemical composition be controlled to lower than 0.43% carbon equivalency. The lower carbon content improves weldability and reduces the potential for stress cracking by hydrogen sulfide typically found in oil and gasoline manufacturing and processing applications.
Another example of supplies tied to a particular utility embrace these for upstream oil and gasoline manufacturing. Many of these purposes happen within the arctic regions of Russia and Canada. For this service, castings are ASME SA 352 Grade LCC, while forgings must meet ASME SA 350 Grade LF2.
Many products with global use now adjust to twin materials specs to satisfy ASME and European requirements. For example, metal castings are specified and authorized to both ASME SA216 Grade WCC and EN 10213 Grade 1.0619. Emerson often provides its personal stringent requirements similar to the warmth treating of high nickel alloys, extra demanding chemical composition or particular welding procedures.
In the previous, Emerson has supplemented typical ASTM and ASME specifications to attain the improved corrosion-resistance levels and high temperature capabilities supplied by high-nickel alloys. This is now completed by the new ASTM specification A990, which addresses both material composition and quality.
Figure 3. Pressure-retaining elements of a valve are subjected to hydrostatic testing to judge the parts’ integrity. Visible leakage or seepage via a casting means automatic rejection.
Qualifying a foundry
As part of a potential foundry’s qualification, Emerson inspects and tests Fisher valve castings. Non-destructive testing radiography is used as a monitoring device. 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 categories D via G, no cracking, sizzling tears or inserts are allowed as laid out in ASTM A990.
High-nickel alloy castings present improved efficiency in corrosive services and elevated temperatures. However, if high-nickel castings are improperly prepared, they will pose major issues, together with poor integrity, poor weldability and lower-than-expected corrosion resistance. pressure gauge ราคา could be adopted to keep away from 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 solid due to the distinction 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 an identical composition weld material. The welder and process for this step should 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 carefully for cracking along the weld heat-affected zone, casting grain boundaries or dendrite boundaries. Failure to meet quality standards will end result within the disqualification of the foundry from additional consideration. Casting patterns must be devoted solely to high-nickel alloy service. Use of carbon steel or a stainless-steel sample is unacceptable because of differences in solidification properties.
Shrinkage rates for gates, risers and other accessories can vary significantly. Once the devoted pattern gear for every of these elements has been secured, try-out castings are poured for every pattern-alloy combination. The castings are then radiographed.
The intent is to disclose any inherent casting defects — corresponding to shrinkage — that need to be eradicated by modifying the pattern rigging.
Figure four. In a foundry evaluation, a casting is full of weld filler, then sliced to yield a bar for bend testing.
A certified 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 accredited and has been delivering high-quality valve body and bonnet castings to Fisher valve manufacturing sites.
To assist ensure 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 international high 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 acquired an Excellent Supplier award from Emerson.
Figure 5. This Chinese foundry meets all specs for casting valve bodies.
Summary
Control valve customers may be involved after they learn certain valve elements are not made in the us or Europe, however elsewhere. Perhaps their concern stems from experience with different inferior merchandise, such as appliances, clothes or electronics made in these nations and sold online. 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 supplier, then users may be assured the valves meet all specifications.
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