Across many forms of products in a variety of industries, the practice of mixing assorted parts from varied resources around the world is the rule, not the exception. Should this be a priority for a management valve user? For instance, when an finish person discovers that a number of components are being made in China (Figure 1), ought to the user worry about the quality?
When coping with a significant valve vendor, the answer is “no.” There shouldn’t be any room for doubt when the seller has a quantity of checks and balances in place specializing in product high quality to ensure control valves function as designed, need minimal maintenance, carry out safely and function inside environmental laws.
Yet, regardless of such efforts by the vendor, a control valve user may have questions on international sourcing and the nation of origin. This article discusses how one main management valve vendor ensures product quality. Many different control valve distributors follow the identical or similar procedures.
Quality specification brings international assurance
Emerson enforces a complete quality specification for its Fisher management valves that should be met by suppliers of pressure-containing and structural metallic castings. The high quality specification consists of greater than a dozen necessities 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 possible supplier’s capacity to fulfill materials specs and applicable worldwide codes and requirements — in addition to particular necessities associated to component manufacture. In the case of castings, a foundry is taken into account “qualified” when it passes a critical evaluation by Fisher’s engineers.
เกจวัดแรงดันเบนซิน must show a document of qualification by a third-party inspection agency and conform to varied requirements, such as ISO 9001:2000, ASME, A2LA, PED and others. It should pass a review of its quality program in addition to on-site audits of the foundry’s processes and procedures similar to welding, heat therapy and non-destructive examination. Additional proof of efficiency is determined 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 requirements. Similarly, every lot of weld filler should adjust to ASME/AWS chemical evaluation specs. In Europe, compliance must be to EN499. Weld filler should 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 sometimes proven 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 scorching tears and cracks, shrink, sand inclusions, veining and rat tails. Mechanical testing involves a hydrostatic pressure take a look at to verify the leak tightness of a management valve’s pressure-retaining elements, together with the physique and bonnet castings. The take a look at procedure involves a fixture that closes off cavities that may be pressurized in service after which subjects the component to the hydrostatic shell test pressure appropriate for the valve physique materials and class.
ASME B16.34 sets out the hydrostatic check strain to use for metal and alloy valves. It’s calculated by multiplying the working stress 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 a half of the valve meeting is a mandatory trigger for rejection (Figure 3).
Compliance with these specs should be ensured, as well as with other requirements relating to supplies.
Figure 2. Markings establish the foundry and supplies of the valve physique. These control valve bodies were cast at an Emerson-approved foundry in China.
Meeting materials requirements
Valve casting integrity and high quality begins with specifications that call not just for premium materials, but also for the supplies that work finest in the meant purposes. These software requirements embrace power and ductility in addition to resistance to sure components, including the make-up of the controlled fluid, operating temperature and circulate velocity.
For instance, chemical composition should be controlled precisely to realize an alloy’s intended performance level. Carbon metal castings for valves supposed for use in oil and gas applications must meet NACE SP0472 recommendations that chemical composition be controlled to lower than zero.43% carbon equivalency. The decrease carbon content improves weldability and reduces the potential for stress cracking by hydrogen sulfide sometimes found in oil and gas manufacturing and processing functions.
Another instance of materials tied to a particular utility embody those for upstream oil and gasoline manufacturing. Many of those applications happen 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 international use now comply with twin material specs to meet ASME and European standards. For example, steel castings are specified and licensed to each ASME SA216 Grade WCC and EN 10213 Grade 1.0619. Emerson often provides its own stringent necessities corresponding to the warmth treating of excessive nickel alloys, more demanding chemical composition or special welding procedures.
In the past, Emerson has supplemented standard ASTM and ASME specs to achieve the enhanced corrosion-resistance ranges and high temperature capabilities supplied by high-nickel alloys. This is now completed by the model new ASTM specification A990, which addresses both material composition and high quality.
Figure 3. Pressure-retaining parts of a valve are subjected to hydrostatic testing to judge the parts’ integrity. Visible leakage or seepage by way of a casting means automated 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 sample. The acceptance criterion is Level 3 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 present improved efficiency 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 course of may be adopted to avoid these casting difficulties.
The foundry should 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 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 filled with an identical composition weld material. The welder and procedure 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 minimize from the plate and bent over a 1½-inch mandrel per ASTM A990 right into a U-shape.
The bars are examined intently 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 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 accessories can differ significantly. Once the dedicated sample equipment for each of these parts 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 — corresponding to shrinkage — that need to be eradicated by modifying the sample rigging.
Figure 4. 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 solid Fisher valve our bodies for more than a decade. After an exploratory go to by procurement and manufacturing specialists, followed by an extensive qualification process, the foundry was accredited and has been delivering high-quality valve physique and bonnet castings to Fisher valve manufacturing sites.
To assist guarantee the standard of the castings it produces, the Chinese foundry has carried out worldwide 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 thrice consecutively within 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 bodies.
Summary
Control valve customers could be involved once they study certain valve components aren’t made in the united states or Europe, but elsewhere. Perhaps their concern stems from expertise with different inferior products, corresponding to home equipment, garments or electronics made in those countries and sold online. But if the valve components are being equipped to a significant management valve vendor that has gone to great lengths to qualify the foundry or supplier, then customers could be assured the valves meet all specifications.
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