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3.1.2

3.1.2. Determining the Fitness of ASME Tanks for Continued Service.

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3.1.2

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  1. 3.1.2 Determining the Fitness of ASME Tanks for Continued Service Plant operational personnel are responsible for maintaining bulk plant equipment and propane storage containers in proper operating condition. A primary job of plant personnel is inspection and preparation of ASME tanks, making them ready and available for installation at customer locations. • In this module you will identify: • Standards for ASME tanks • Features of stationary ASME tanks • Valves & fittings on ASME tanks • Conditions that require tank fitting replacement, tank repairs or removal from service • Characteristics & features of ASME mobile and motor fuel tanks

  2. Identifying Standards for ASME Tanks All ASME tanks are steel containers manufactured using fusion welding processes with threaded or flanged couplings provided for installation of valves and fittings.Propane tanks are built to standards set out in theBoiler and Pressure Vessel Code of the American Society of Mechanical Engineers. Figure 1. ASME Unfired Pressure Vessel “Clover Leaf” Data Plate Marking

  3. NFPA 58 NFPA 58 2001 2004 Identifying Standards for ASME Tanks Valve and fitting requirements for ASME tanks are found in columns 5 and 6 of Table 2.3.3.2(a) of NFPA 58, LP-Gas Code. Specific valve and fitting requirements are found in other sections of Chapter 2. Valve and fitting requirements for ASME tanks are found in columns 5 and 6 of Table 5.5.7.1 of NFPA 58, LP-Gas Code. Specific valve and fitting requirements are found in other sections of Chapter 5.

  4. Features of Stationary ASME Tanks Design Information – ASME tanks have design information stamped on a data plate attached to the tank. Figure 2b. Underground Tank Data Plate Figure 2a. Aboveground Tank Data Plate

  5. Features of Stationary ASME Tanks Inspection Requirements – Although ASME tanks are not required to pass specific periodic tests or requalification as DOT tanks and cylinders are, they should always be inspected to be sure that they are in safe working condition before filling and in the process of preparing them for installation.

  6. Features of Stationary ASME Tanks Tank Capacity – ASME tanks are categorized by the maximum amount of water (in gallons) they will hold. A tank that has a maximum water capacity of 1,000 gallons (expressed 1,000 gallons W.C.) has 800 gallons propane capacity allowing 20% vapor space for liquid thermal expansion. Residential customers use 120, 250, 320, 500, or 1,000 gallon W.C. tanks.

  7. Features of Stationary ASME Tanks Hazardous Materials Markings– Unlike cylinders, most residential customer ASME tanks used for storing propane are not required to have hazardous material markings displayed on them except during the time they contain propane and are being transported on public roads. Figure 3b. LP-Gas Placard [The hazard class (2) or division (2.1) may be used on placards.] Figure 3a. FLAMMABLE GAS “4 by 4” Label

  8. Identifying Valves & Fittings on ASME Tanks The valve fittings on ASME tanks vary in number, size and location for aboveground and underground tanks and according to the size of the tank. Figure 4a. Aboveground Tank Figure 4b. Underground Tank

  9. Identifying Valves & Fittings on ASME Tanks Figure 5. ASME Tank (Aboveground Installation)

  10. Identifying Valves & Fittings on ASME Tanks Figure 6. Riser and Combination Valve (Underground Installation)

  11. Identifying Valves & Fittings on ASME Tanks Relief Valves External Pressure Relief Valves Figure 7. External Pressure Relief Valve

  12. Identifying Valves & Fittings on ASME Tanks Relief Valves Internal Spring-Type Pressure Relief Valves Courtesy of Rego and Sherwood Figure 8. Internal Spring-Type Pressure Relief Valves

  13. Identifying Valves & Fittings on ASME Tanks Relief Valves – Using a reducing bushing with a pressure relief valve is not allowed, and tampering with the setting of a relief valve is prohibited. Figure 9. Pressure Relief Valve Markings

  14. Identifying Valves & Fittings on ASME Tanks • Relief Valves – Pressure relief valves are marked with important information used to ensure that they are correctly sized and appropriate for the tank. Three important relief valve markings must be understood: • Manufacturer's date code • Start-to-discharge pressure rating (ASME or UL) • Flow capacity rating (ASME or UL)

  15. Identifying Valves & Fittings on ASME Tanks Service Valves – Service valves serve two functions: controlling the flow of gas out of a tank, and providing a special connection fitting for the pressure regulator. Figure 10. Stationary ASME Tank Service Valve

  16. Courtesy of Sherwood Identifying Valves & Fittings on ASME Tanks Combination Service Valve and Vapor Equalizing Valve– Figure 11. (“Multi-Valve”) Combination of Service Valve, Vapor Equalizing Valve, and Maximum Fixed Liquid Level Gauge

  17. Identifying Valves & Fittings on ASME Tanks Filler Valves– Courtesy Fisher Controls Co. Courtesy of Sherwood Figure 12. Double Back-Check Filler Valve

  18. Identifying Valves & Fittings on ASME Tanks Vapor Equalizing Valves– A vapor equalizing valve is used to equalize the vapor pressure between two containers when liquid propane is being transferred from one container to the other. Figure 13. Vapor Equalizing Valve

  19. Identifying Valves & Fittings on ASME Tanks Actuated Liquid Withdrawal Excess-Flow Valves– are used to remove liquid propane from stationary tanks for transportation or during valve replacement. Courtesy Fisher Controls Co. Courtesy of Sherwood Figure 17. Actuated Liquid Withdrawal Excess-Flow Valve

  20. Identifying Valves & Fittings on ASME Tanks Figure 14. Older ASME Tank With Fill to Liquid Space— Evacuation Through Filler Valve

  21. Identifying Valves & Fittings on ASME Tanks Figure 15. Newer ASME Design with Separate Evacuation Fitting

  22. Identifying Valves & Fittings on ASME Tanks Figure 16. Filling Methods

  23. Identifying Valves & Fittings on ASME Tanks Actuated Liquid Withdrawal Excess-Flow Valves Courtesy of REGO Figure 18a. Chek-Lok 7590U/7591U Schematic Drawing Figure 18b. Connecting the Chek-Lok and Unloading Adapter and Valve

  24. Conditions that Require Tank Fitting Replacement, Tank Repairs or Removal from Service Be sure that you read, understand, and apply any company policies and procedures for maintaining ASME tanks and other containers used for customer propane storage. Particular attention should be given to company-specific standards that stipulate requirements for condition of container coating, customer information decals, sealing of container valves when not in service, and inspection of container valves, fittings, regulators, and other container appurtenances.

  25. Conditions that Require Tank Fitting Replacement, Tank Repairs or Removal from Service • 5-Step Process for Inspecting ASME Tanks • 1. Verifying Proper Working Pressure and Data Plate Information – • Examine the data plate to ensure that all required information is present and readable. • ASME stationary tanks must have a minimum working pressure of 250 psig (200 psig for certain ASME tanks built before 1950).

  26. Conditions that Require Tank Fitting Replacement, Tank Repairs or Removal from Service • 5-Step Process for Inspecting ASME Tanks • 2. Checking Welds and Fittings for Leaks – • Vacuum purged tanks Figure 20. Using a Vacuum Gauge To Check for Leakage of New Tank Figure 19. New Vacuum Purged ASME Tank

  27. Conditions that Require Tank Fitting Replacement, Tank Repairs or Removal from Service • 5-Step Process for Inspecting ASME Tanks • 2. Checking Welds and Fittings for Leaks – • Propane vapor pressurized tanks Figure 21. Using Leak Detector Solution

  28. Conditions that Require Tank Fitting Replacement, Tank Repairs or Removal from Service Only the tank manufacturer or a certified ASME repair facility can repair defective welds or other shell or head defects such as excessive corrosion. Figure 22a. Weld Leak Figure 22b. Labeling Leak Location

  29. Conditions that Require Tank Fitting Replacement, Tank Repairs or Removal from Service • 3. Verifying Proper Working Order of Valves and Fittings – • Relief Valves: verify proper discharge pressure and volume Figure 23a. Inspection of Internal Pressure Relief Valves Figure 23b. Inspection of External Pressure Relief Valves

  30. Conditions that Require Tank Fitting Replacement, Tank Repairs or Removal from Service • 3. Verifying Proper Working Order of Valves and Fittings – • Service Valves: most common problem a leaking valve seat or packing seal Figure 24. Inspection of Service Valves

  31. Conditions that Require Tank Fitting Replacement, Tank Repairs or Removal from Service • 3. Verifying Proper Working Order of Valves and Fittings – • Filler Valves Figure 25. Filler Valve Inspection

  32. Conditions that Require Tank Fitting Replacement, Tank Repairs or Removal from Service • 3. Verifying Proper Working Order of Valves and Fittings – • Vapor Equalizing Valves Figure 26. Inspection of Equalizing Valves

  33. Conditions that Require Tank Fitting Replacement, Tank Repairs or Removal from Service • 3. Verifying Proper Working Order of Valves and Fittings – • Actuated Liquid Withdrawal Excess-Flow Valves Figure 27. Inspection of Withdrawal Valves

  34. Conditions that Require Tank Fitting Replacement, Tank Repairs or Removal from Service • 4. Examining Tank Heads and Shell for Defects or Damage • Cracks • Dents • Bulges • Cuts or Gouges • Corrosion • Fire Damage

  35. Conditions that Require Tank Fitting Replacement, Tank Repairs or Removal from Service • Fire Damage – Common evidence of exposure to fire is • charring or burning of the paint or other protective coat • burning or scarring of the metal • distortion • burning or melting of the valves • Tanks that have been involved in a fire and show no distortion shall be requalified for continued service by retesting using the hydrostatic test procedure applicable at the time of original fabrication.

  36. Conditions that Require Tank Fitting Replacement, Tank Repairs or Removal from Service • 5. Evaluating the Tank’s Protective Coating – An underground tank that has been in service and excavated must be thoroughly cleaned of adhering soil, and its coating thoroughly cleaned and checked for areas where the coating did not bond to the tank metal.

  37. Conditions that Require Tank Fitting Replacement, Tank Repairs or Removal from Service Figure 28. Excavated Underground Tank Requiring Cleaning and Re-Application of Protective Coating

  38. Conditions that Require Tank Fitting Replacement, Tank Repairs or Removal from Service • Protective coatings on aboveground tanks should be evaluated for: • Acceptable general appearance • Flaking or pitting • Loss of pigment • Failure to bond • Evidence of underlying metal corrosion

  39. Characteristics of ASME Mobile & Motor Fuel Tanks • Valves and fittings are protected by heavy metal guards and/or they are recessed within the profile of the tank. • They have mounting hardware designed for attachment to the vehicle. • The sizes of the openings for threaded valve fittings are limited to ¼”, ¾”, and 1” female NPT—usually a maximum of 5 threaded openings. • New mobile and motor tanks have higher design pressures than stationary tanks. • Most motor fuel tanks have 312 psig working pressures.

  40. Characteristics of Motor Fuel Tanks Liquid Service Valve– The liquid service valve has an internal excess flow valve that is normally in the open position, allowing liquid to flow to the engine. Figure 29a. Cutaway View of Excess Flow Figure 29b. Liquid Service Valve

  41. Characteristics of Motor Fuel Tanks 1¾-inch Acme Filler Valve Figure 30a. Filler Valve Figure 30b. Motor Fuel Tank Cut-Away with Stop-Fill Valve

  42. Characteristics of Motor Fuel Tanks Fixed Maximum Liquid Level Gauge Figure 31. Fixed Liquid Level Gauge

  43. Characteristics of Motor Fuel Tanks Pressure Relief Valve Figure 32. Internal Pressure Relief Valve

  44. Characteristics of Motor Fuel Tanks Float Gauge Figure 33. Motor Fuel Tank Valve & Float Gauge Protection

  45. Characteristics of Motor Fuel Tanks Float Gauge Figure 34b. Dial Face & Mounting Figure 34a. Float Gauge Construction

  46. Characteristics of Motor Fuel Tanks Motor Fuel Valve and Fitting Enclosures– Motor fuel tanks located within the vehicle must have a vapor-tight enclosureto isolate valves & fittings and to covey any vapor to the outside. Figure 35. Vapor-Tight Motor Fuel Tank Valve Enclosure (Remote Filler Valve & Fixed Liquid Gauge Outage at Bottom)

  47. Characteristics of Mobile Fuel Tanks Mobile fuel tanks are similar to motor fuel tanks except that they do not supply fuel to the vehicle engine. They are designed to supply propane vapor to appliances used in recreational vehicles, campers, and catering trucks. Figure 36. Mobile Fuel Tank Valves and Fittings

  48. Characteristics of Mobile Fuel Tanks Mobile and motor fuel tanks should be inspected to determine if they are fit for installation or continued service applying the same inspection methods and criteria used for stationary tanks. Figure 37. Concealed Mobile Fuel In Ventilated Cabinet on an RV

  49. Time to See If You Got the Key Points of This Module… • Complete the Review on pages 29 - 31. • See if you are ready for the Certification Exam by checking off the performance criteria on pages 32 & 33.

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