MODULE 8 Cylinder Safety
Module 8 – Cylinder Safety Introduction You must be familiar with inspection guidelines and filling procedures when working with propane cylinders. Following these guidelines is essential to safety when handling, transporting, and delivering cylinders to your customers. After completing this module, you will be able to: • Explain inspection requirements for propane cylinders. • Describe which actions to take when a cylinder is rejected. • Discuss best practices for filling cylinders. • Identify the requirements for cylinder repair and condemnation. • Identify a composite propane cylinder and how its design differs from steel and aluminum cylinders.
LESSON 1 Filling Methods
Filling Methods Introduction Before cylinders can be transported, they must be inspected and filled according to all applicable regulations and safe industry practices. Following these practices will help ensure the safe filling, transportation, and delivery of propane cylinders. After completing this lesson, you will be able to: • Identify the procedures to perform visual inspections of cylinders. • Identify the steps for setting scale weight. • Identify the steps for filling cylinders by weight and by volume. • Identify composite cylinders.
Visual Inspection You must visually inspect every cylinder when it first arrives at the bulk plant and before every filling and installation to verify it is safe for continued service. Follow these steps to perform a visual inspection of a cylinder: • Verify the cylinder is within the qualification date. • Make sure the cylinder has the required markings and labels. • Determine the overall fitness of the cylinder.
Visual Inspection, cont. To determine the overall fitness of the cylinder, you must check for: • Leaks. • Bulges, gouges, or dents. • Detrimental rusting or corrosion. • Defective valves or safety devices. • Damage to the foot ring, collar, or protective ring. • Evidence of fire or heat damage. If a cylinder has any of these or other signs that it may not be safe, do not use it. The cylinder must either be repaired and requalified, or condemned. Requalification will be discussed later in this module.
Transfer Requirements DOT requires that at least one qualified attendant remain close to the transfer operation during filling. While attending, you must be alert for leaks or any other problems that might occur. You can check for leaks with an approved leak detector solution. If you notice a leak, stop filling immediately and shut off the pump. If the leak is coming from the cylinder, it must be repaired and, in some cases, requalified, before it can be filled again. Cylinders can be filled only in the open air or in well-ventilated buildings specifically designed for that purpose. Containers marked “single trip” or “nonrefillable” must not be refilled. It is not recommended to vent propane liquid or vapor when filling cylinders by weight. This creates additional hazards and does not speed up the filling process. Always refer to your company’s policy and procedures when filling cylinders.
Filling Methods Propane cylinders can be filled either by weight or by volume. Everyone responsible for filling cylinders must follow DOT regulations regarding proper filling methods for propane. Filling by Weight A cylinder must be filled by weight if it is transported in commerce and has a water capacity under 200 lb. Filling by Volume Cylinders with a water capacity of 200 lb or greater can be filled by volume prior to transport. Cylinders weighing less than200 lb can be filled by volume only if they are not to betransported in commerce and your state or municipality permits it. Let’s review procedures you might follow when filling cylinders by weight and by volume. And remember, always refer to your company policy for any additional or different procedures it may have.
Setting Scale Weight To fill a propane cylinder by weight, you must set the scale correctly. Follow these steps to determine the total fill weight of a cylinder: • Look for the water capacity (WC) and tare weight (TW) mark stamped on each cylinder or its protective collar. Water capacity is the amount of water, in pounds, that the cylinder will hold when the container is filled to its maximum capacity. Tare weight is the weight of the empty container, including the cylinder valves. • Determine the propane capacity from a conversion table. If you don’t have access to a conversion table, you can determine the propane capacity by using this formula: WC(lb) x .42 = propane capacity (lb)
Setting Scale Weight, cont. For example, if a particular cylinder has a water capacity of 80 lb; it can safely hold 33.5 lb of propane. The calculation is: 80 lb X .42 = 33.5 lb of propane. • Add the cylinder’s tare weight, maximum propane capacity, and the weight of the filling hose or nozzle. The sum of these three weights determines the scale’s set point. • Set the scale to this weight and begin filling the cylinder. As soon as the filling weight reaches the scale’s set point, immediately stop the filling process.
LEARNING ACTIVITY Calculating Scale Weight Step-by-Step – Filling Portable Cylinder by Weight
Filling Cylinders by Volume DOT permits cylinders to be filled by volume if they have water capacities in excess of 200 lb. Smaller cylinders can be filled by volume as long as they are not transported in commerce. For example, a 20 lb grill cylinder can be filled by volume at a local gas station as long as the customer transports his/her own cylinder. That same cylinder would have to be filled by weight if a propane marketer transported it to a reseller or the customer. Follow these steps when filling cylinders by volume: • Open the appropriate liquid outlet and by-pass return valves on the cargo or storage tank as necessary. • Open the vent valve on the fixed maximum liquid level gauge to check the level of propane in the cylinder. • Connect the hose to the filling connection such as the filler valve or service valve as appropriate.
Filling Cylinders by Volume, cont. • Start the pump and slowly open the valve on the end of the hose. 5. Open the service valve on the cylinder if filling through this connection. • When a white mist appears from the fixed maximum liquid level gauge, immediately close the hose end valve. • Close the cylinder service valve (if using this connection to fill), disconnect the hose, and store it properly. • Check the cylinder for leaks and apply any DOT or hazard warning labels as necessary.
Pressure-relief Valves You may not transport a cylinder unless it is equipped with at least one pressure-relief valve. A pressure- relief valve is designed to open and release to the atmosphere high pressures that may build within the cylinder. Check the condition of the pressure relief valve before filling and transportation. Check for physical damage, rust, debris, or leakage, and ensure the valve is fitted with a dust cap or plug to protect it from contamination. NOTE: Never look directly into the bore of a pressure relief valve as the valve could open without warning and injure you. Inspect the valve’s inner workings from an angle or use a pocket mirror.
Composite Cylinders Composite cylinders are DOT-specification containers introduced recently to the U.S. market. These cylinders are constructed of material such as fiberglass and reinforced with Kevlar® or carbon fiber. The pressure vessel component of the cylinder is encased in a high impact plastic outer shell. Common applications include barbeque grills and forklifts. Composite cylinders are up to 40% lighter than their steel counterparts and are very corrosion-resistant. They are made in either one- or two-piece designs. Many of the composite cylinders in service today are translucent, making it possible to see the liquid level inside. The following lists some other important aspects of composite cylinders: • They are equipped with an Overfill Prevention Device (OPD). • The maximum filling limit by weight of propane in nonengine fuel applications is 42% of the cylinder’s water capacity. • They must be equipped with a pressure relief valve. Fusible plugs are not allowed.
Composite Cylinders, cont. Composite cylinders are limited to a 15-year life cycle and require requalification by visual inspection and proof pressure tests every 5 years. These cylinders are lighter than steel cylinders, and their filling density for nonmotor fuel applications is 42%. Accordingly, if they are filled by weight, the total filled weight (tare weight plus propane weight) will be much less than a comparable steel cylinder. Ask your supervisor for further instructions on servicing these cylinders. You should treat these cylinders as you would any other cylinder. Carefully inspect them for damage, appropriate markings, and a current requalification date.
LESSON 2 Cylinder Qualification
Cylinder Qualification Introduction Cylinders in propane service are built according to DOT standards. As with all DOT-specification containers, cylinders must be requalified periodically to remain in service. Cylinders that go beyond their requalification time limit must not be refilled. Even a cylinder still within its requalification time limit may need to be requalified. Evidence of physical abuse, rust, corrosion, or fire damage will require requalification before it can be used again. Aluminum and composite cylinders subjected to fire must be removed from service immediately. It is highly recommended that each facility that visually requalifies cylinders has a copy of the applicable pamphlets published by the Compressed Gas Association (CGA), or the pertinent information readily available to its employees.
Cylinder Qualification Introduction, cont. After completing this lesson, you will be able to: • Explain the importance of cylinder requalification. • Explain the three cylinder requalification methods. • Identify the requirements of an external visual cylinder inspection.
Cylinder Requalification Every propane cylinder is pressure tested after manufacturing. Each cylinder must also be inspected before every propane filling. A cylinder must also be requalified for continued use. Depending on the requalification method and the cylinder’s specifications, it must be requalified every 5, 7, or 12 years. Refer to Title 49 CFR §180 to determine requalification deadlines for the type of cylinder you are requalifying. Never fill or use a cylinder that is beyond its requalification time limit. The most recent requalification date is either marked on the cylinder or on a label affixed to it.
Cylinder Requalification, cont. This marking includes: • The month and year of the last requalification. • The Requalification Identification Number (RIN). • A single letter indicating the requalification method that was used (unless a hydrostatic test). Since 2008, DOT has been issuing new and renewed RINs that contain a letter and six numbers. This RIN may be on a label rather than stamped on the cylinder. If a company uses a RIN that contains a letter and four numbers, it does not qualify for the label exception and the RIN must be stamped on the cylinder. Keep in mind that when a cylinder is relatively new the most recent “requalification” date may be the manufacturer’s original test date.
Requalification Methods There are three ways to requalify a cylinder. The requalification method used is stamped with the date on each cylinder. • Hydrostatic Test: A date without a letter indicates the cylinder was subjected to a complete water jacket hydrostatic test. The next requalification must be within 12 years. For example, a cylinder marked “10/08” tells the technician that this cylinder was hydrostatically requalified in October 2008. • Proof Pressure Test: A date followed by the letter “S” indicates a proof pressure test has been performed. The next requalification must be within 7 years. For example, a cylinder marked “03/08S” tells the technician that this cylinder was proof pressure tested and requalified in March 2008.
Requalification Methods, cont. • External Visual Inspection (CGA Inspection Method): A date followed by the letter “E” indicates an external visual inspection was performed. The next requalification must be within 5 years. For example, a cylinder marked “02/09E” tells the technician that this cylinder was requalified by the external visual inspection method in February 2009. Most propane companies use the visual inspection method for requalification. Cylinders that require hydrostatic or proof pressure retesting are typically sent to a company specializing in these tests. After retesting, the requalifier marks the cylinder with a test date, type of requalification method used, the RIN number, and other important markings.
External Visual Inspection Only cylinders with select specification designations may be requalified by using the external visual inspection method. These designations include: • DOT-3A • DOT-3AA • DOT-3A480X • DOT-3B • DOT-4B • DOT-4BA • DOT-4BW • DOT-4E. External visual requalification inspections can be made only by a qualified person working in a facility that has a current RIN. The RIN must be placed on the cylinder above, below, or before the date and type of inspection.
External Visual Inspection Recordkeeping Any cylinder found to be damaged or missing required markings must be condemned and placed out of service. Whether or not the cylinder passes requalification, you must record and keep a copy of the results. Those records must include: • Date of inspection (month and year). • DOT specification number. • Cylinder identification (registered symbol and serial number, date of manufacture, and owner).
External Visual Inspection Recordkeeping, cont. • Type of cylinder protective coating. • Conditions of cylinder checked (any leakage, corrosion, gouges, dents, or fire damage). • Disposition of cylinder (returned to service, returned to manufacturer for repair, or condemned). Required requalification markings must be legible and readily visible at all times. They may be placed on any part of the upper end of the cylinder, excluding sidewalls, unless specifically permitted. Additional dates may be marked on the external surface of the foot ring.
LESSON 3 Important DOT Requalification Terms
Important DOT Requalification Terms Introduction The conditions of cylinders and other terms related to them are clearly defined by DOT regulations. They are: Condemned Unserviceable to transport hazardous materials, and may not be restored by repair, rebuilding, requalification, or any other procedure. Defective Has an imperfection requiring its removal from service. Filled or charged Has had a hazardous material introduced into it. Repair Procedure for correction of a rejected cylinder that may involve welding.
Important DOT Requalification Terms Introduction Rejected Cannot be in service without repair, rebuilding, and requalification. Requalification The process of completing a visual inspection and/or tests to determine its suitability for continued service. Visual Inspection An internal or external visual examination, or both, performed as part of the requalification process. After completing this lesson you will be able to: • Explain the importance of cylinder repair. • Explain the importance of cylinder condemnation.
Cylinder Repair When a cylinder has been inspected, it may be necessary to repair it before it can be requalified. Clearly identifying the repair status on the cylinder will allow it to be transported for repair, but not put into service. After repair, it must be re-inspected and either requalified or condemned. Minor repairs such as those to the cylinder collars, foot rings, valves, and fittings, may be performed by trained employees. Never weld, heat, or otherwise recondition cylinders, especially on the pressure component such as a side wall. This activity should be performed only at qualified cylinder repair facilities. Steel cylinders that have been exposed to fire or obvious overheating should be sent to a cylinder repair facility for evaluation and repair. Aluminum cylinders that have been exposed to fire or overheating must be permanently removed from service. Always look for signs of charring or burned paint as evidence of overheating. When you are in doubt of the cylinder’s integrity, condemn it and remove it from service.
Cylinder Condemnation If a cylinder is found to be unfit for continued propane service, it must be condemned and clearly marked as such. A cylinder is condemned when: • It leaks through a pressure-bearing wall. • Repairs cannot be made. • It is likely weakened through cracking. • It meets the rejection criteria in Title 49 CFR §180. All conditions for condemnation can be found in the applicable CGA pamphlets.
Cylinder Condemnation, cont. When a cylinder is condemned, the inspecting technician uses a steel stamp or scribe to place a series of Xs over the DOT specification number. The service pressure marking should also be stamped or scribed over with the word “CONDEMNED.” Alternatively, the requalifier may render the cylinder incapable of holding pressure. For composite cylinders, a label with the word “CONDEMNED” must be applied and over-coated with epoxy. This must be near, but not obstructing, the original manufacturer’s label. Never remove or obscure the “CONDEMNED” marking on a cylinder. Once a cylinder has been condemned, it must never again be filled or used.