Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D23/00—Producing tubular articles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D19/00—Casting in, on, or around objects which form part of the product
  • B22D19/06—Casting in, on, or around objects which form part of the product for manufacturing or repairing tools
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
  • F16K27/00—Construction of housing; Use of materials therefor
  • F16K27/06—Construction of housing; Use of materials therefor of taps or cocks

Definitions

• the present invention relates generally to valves having a stemmed plug and more particularly to double block and bleed plug valves wherein the plug and stem are made of different materials.
• Today's valve plugs are cast of one uniform material. Usually the trunnions (upper and lower) are cast integrally with the body of the plug. Sometimes, depending on structural requirements or producibility choices, the trunnions are welded on and generally a structured superior metal is used, but generally, not a more corrosion resistant material. The upper trunnion is the only portion of the plug that penetrates the pressure vessel and is therefore generally considered (but not code required) as qualifying as pressure containing.
• code does not require the material to be an approved pressure vessel material.
• some valve manufacturing companies have chosen the cast plug material to be of pressure vessel quality just to obtain trunnion material of pressure vessel quality.
• Other companies less concerned about the risk of catastrophic failure have not chosen pressure vessel quality material, but instead have selected low cost iron which indeed is inexpensive and exhibits good bearing properties, but provides cast iron trunnions which are not suitable for hazardous application due to their propensity to catastrophic failure.
• the optimum material combination in a plug having stems would be American Iron and Steel Institute 410 SS trunnion/stem which is commonly used for a variety of valve stems in the industry for its high strength, toughness, pressure vessel quality, corrosion resistance, availability, wear resistance, etc. and a plug body of ductile iron (Dl) since it is inexpensive (about 40% less than WCB grade carbon steel) and displays good strength and excellent wear and anti-galling properties important for slip support and movement.
• Dl ductile iron
• One embodiment of the invention was constructed by pouring molten Dl around a variety of stem configurations, i.e., all of which passed the mechanical requirements test even with no mechanical joint.
• Iron plug body displays good wear and anti-galling characteristics
• Cost is reduced by about 40%;
• New and old plugs may be interchangeable
• both upper and lower stems may be installed; b) stem does not need plating, surface treatment or coating to inhibit corrosion; c) stem pin hole, which is difficult for corrosion inhibitor access, will not rust to stem pin; d) bar stock does not have sand pockets so the stem finish will be superior;
• FIG. 1 is a partially phantom, partially cross-sectional view of a plug valve having a plug assembly shown in a finished condition in accordance with a preferred embodiment of the invention.
• FIG. 2 is a partially cross-sectioned view of the plug assembly of FIG. 1 with the trunnion shown in the raw or "as cast” condition.
• a double block and bleed plug valve 10 comprises an inlet 12, an outlet 14 and a body 15. Within body 15 there is a rotatably and vertically translatable plug 16 having opposing slips 18 and 20. Plug 16 provides a flow passage 22 which when aligned with inlet 12 and outlet 14, permits flow through valve 10. The position of plug 16 and thus passage 22 is determined by control of a stem 24. It is the material of which the plug 16 and stem 24 are made and their means of interconnection, that constitute the inventive features of the present invention.
• plug 16 is made of ductile iron and stem 24 is made of 410 stainless steel.
• the manner of interconnection is by surface molecular bonding which occurs when the stainless steel stem is placed in the casting mold for the plug.
• the mold is then filled with molten ductile iron such as at a temperature of 2,950 ° F.
• the molten iron forms the plug and surrounds the stem.
• a hole 25 in the stem is also filled with iron forming a pin 26.
• the principal form of interconnection to form an integral plug assembly having an iron plug and a steel stem is surface molecular bonding between the two components.
• the resultant assembly of a ductile iron plug and stainless steel stem provides superior characteristics in the plug operation as well as in the stem quality as outline above.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Lift Valve (AREA)
• Mechanically-Actuated Valves (AREA)
• Taps Or Cocks (AREA)
• Connection Of Plates (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=24511432

Family Applications (1)

Country Status (8)

Families Citing this family (2)

Family Cites Families (5)

• 2001
  • 2001-07-24 MX MXPA02003327A patent/MXPA02003327A/es unknown
  • 2001-07-24 CN CN01802201A patent/CN1386079A/zh active Pending
  • 2001-07-24 KR KR1020027003994A patent/KR20020068510A/ko not_active Application Discontinuation
  • 2001-07-24 BR BR0107089-4A patent/BR0107089A/pt not_active Application Discontinuation
  • 2001-07-24 WO PCT/US2001/023363 patent/WO2002010620A2/en not_active Application Discontinuation
  • 2001-07-24 EP EP01954945A patent/EP1303372A2/de not_active Withdrawn
  • 2001-07-24 JP JP2002516513A patent/JP2004505226A/ja active Pending
  • 2001-07-24 CA CA002385773A patent/CA2385773A1/en not_active Abandoned

Non-Patent Citations (1)

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