Across many types of products in quite lots of industries, the practice of mixing assorted elements from various assets around the world is the rule, not the exception. Should this be a concern for a management valve user? For example, when an end person discovers that a number of components are being made in China (Figure 1), ought to the person fear about the quality?
When coping with a major valve vendor, the answer is “no.” There shouldn’t be any room for doubt when the vendor has multiple checks and balances in place specializing in product high quality to ensure management valves function as designed, need minimal upkeep, carry out safely and operate within environmental laws.
Yet, regardless of such efforts by the seller, a control valve user may have questions about global sourcing and the nation of origin. This article discusses how one main management valve vendor ensures product quality. Many other management valve distributors observe the identical or comparable 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 steel castings. The high quality specification consists of greater 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 endure a rigorous qualification process. The process thoroughly investigates a possible supplier’s ability to fulfill material specifications and applicable international codes and requirements — as nicely as particular requirements associated to part 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 demonstrate a record of qualification by a third-party inspection company and conform to numerous standards, corresponding to ISO 9001:2000, ASME, A2LA, PED and others. It must cross a evaluate 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 decided by analysis of tryout castings to verify specifications are met.
Welding procedures — Welding is used during the manufacturing and upgrading of castings, similar to when radiographic examination is required. Welding requirements state that procedures and welder qualifications must meet ASME Section IX (or EN ISO 15614-1 and ISO 9606-1) qualification standards. Similarly, every lot of weld filler should comply with ASME/AWS chemical analysis specs. In Europe, compliance should be to EN499. Weld filler must have actual 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 can also be typically shown on the physique casting, corresponding to CC, CF8M, CN7M and others.
Casting checks — Emerson technicians conduct both visible inspections and mechanical exams on pressure-retaining castings.
As-cast exterior and internal surfaces are inspected visually for unacceptable irregularities, together with sizzling tears and cracks, shrink, sand inclusions, veining and rat tails. Mechanical testing entails a hydrostatic pressure take a look at to substantiate the leak tightness of a control valve’s pressure-retaining elements, including the body and bonnet castings. The take a look at process includes a fixture that closes off cavities that may be pressurized in service and then subjects the part to the hydrostatic shell check pressure applicable for the valve physique materials and class.
ASME B16.34 units out the hydrostatic test pressure to make use of for metal and alloy valves. It’s calculated by multiplying the working pressure by 1.5 and rounding to the next larger 25 psig increment. Any visually detectable weeping or leaking through the strain boundary walls which are part of the valve meeting is a mandatory cause for rejection (Figure 3).
Compliance with these specs have to be ensured, as nicely as with different necessities concerning supplies.
Figure 2. Markings determine the foundry and materials of the valve body. These management valve our bodies were forged 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 in addition for the materials that work best within the supposed applications. These utility necessities include power and ductility in addition to resistance to sure factors, including the makeup of the managed fluid, operating temperature and flow velocity.
For occasion, chemical composition have to be controlled precisely to attain an alloy’s supposed efficiency level. Carbon metal castings for valves meant for use in oil and fuel purposes must meet NACE SP0472 recommendations that chemical composition be controlled to less than zero.43% carbon equivalency. The lower carbon content material improves weldability and reduces the potential for stress cracking by hydrogen sulfide usually found in oil and gas production and processing purposes.
Another example of supplies tied to a particular software embrace those for upstream oil and fuel production. Many of those purposes occur 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 merchandise with international use now adjust to twin materials specifications to fulfill ASME and European requirements. For instance, steel castings are specified and authorized 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 high nickel alloys, more demanding chemical composition or special welding procedures.
In the past, Emerson has supplemented standard ASTM and ASME specifications to achieve the enhanced corrosion-resistance ranges and high temperature capabilities supplied by high-nickel alloys. This is now accomplished by the model new ASTM specification A990, which addresses each materials 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 via a casting means automated rejection.
Qualifying a foundry
As part of a prospective foundry’s qualification, Emerson inspects and checks Fisher valve castings. Non-destructive testing radiography is used as a monitoring tool. ASTM A990 Class C requires radiography of the primary casting of every sample. The acceptance criterion is Level 3 for classes A, B and C. For classes D via G, no cracking, scorching 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 main issues, together with poor integrity, poor weldability and lower-than-expected corrosion resistance. A systematic foundry qualification course of can be followed to avoid these casting difficulties.
The foundry should cast a 1-inch thick high-nickel test plate (Figure 4) that meets ASTM Material Specification A990. It’s tough to solid due to the difference in cross-section between the bottom 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 must meet the standards 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 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 meet quality requirements 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 metal or a stainless-steel sample is unacceptable as a result of differences in solidification properties.
เกจวัดแรงดันไนโตรเจนราคา for gates, risers and different equipment can range significantly. Once the dedicated sample tools for every of those 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 — similar to shrinkage — that have to be eliminated by modifying the pattern rigging.
Figure four. In a foundry analysis, a casting is crammed 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 visit by procurement and manufacturing specialists, followed by an in depth 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 carried out 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 3 times 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 bodies.
Summary
Control valve customers may be involved once they learn sure valve components are not made in the united states or Europe, but elsewhere. Perhaps their concern stems from experience with different inferior products, similar to appliances, garments or electronics made in these nations and bought online. But if the valve components are being provided to a significant control valve vendor that has gone to nice lengths to qualify the foundry or supplier, then users could be assured the valves meet all specifications.
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