Luxfer Carbon Composite Cylinders INSPECTION MANUAL
Luxfer Carbon Composite CylindersINSPECTION MANUAL 2009PART 1: A guide to the use, maintenance and periodic inspectionof Luxfer fully wrapped carbon composite cylinders with a designlife of 15 years in the U.S.A. and Canada
ContentsIntroduction.3Luxfer: Setting the Standard Worldwide .41. Cylinder design and specifications .51.1 Special Permits .72. Design and performance criteria .82.1 Design criteria .83.2 Qualification testing.83. Manufacture .103.1 Aluminum-alloy liners.103.2 Inspection procedures .103.3 Composite overwrapping .113.4 Cylinder lot inspection and testing .113.5 Independent inspection authorities .123.6 Marking and labeling.123.7 Protective end caps and boots .134. Cylinder use .144.1 General .144.2 Approved gases .154.3 Cylinder filling .165. Periodic inspection and requalification .175.1 General .175.2 Exterior inspection .175.3 Valve removal .215.4 Internal inspection.225.5 Pressure testing .236. Cylinder damage criteria .246.1 General .246.2 Abrasion damage.246.3 Cuts.266.4 Impact damage .286.5 Delamination .306.6 Heat or fire damage .306.7 Structural damage .346.8 Chemical attack .347. Repair procedure.358. Final operations .378.1 Drying and cleaning .378.2 Repainting.388.3 Valve insertion .38TABLE 2: Recommended Valve Torque Range .398.4 Destruction of condemned or expired cylinders.409. Summary .41Care and maintenance of a Luxfer carbon composite cylinder.41APPENDIX 1: Sample labels.42APPENDIX 2: Removal and refitting of protective caps, boots .432
IntroductionThis guide is intended for use with Luxfer fully wrapped carbon composite cylinders with adesign life of 15 years, which are cylinders manufactured to DOT Special Permit SP 10915 andTransport Canada permit of Equivalent Safety SU 5134.Luxfer cylinders with a design life of up to 30 years are manufactured in accordance with DOTSP 14232. Part 2 of the Inspection Manual covers use, maintenance and periodic inspection ofthese designs.High-pressure carbon composite cylinders are durably designed for the hard service they receive.Nevertheless, like all compressed gas equipment, cylinders must be treated, maintained andinspected properly. This users’ manual will assist suitably trained personnel to operate, valve,inspect and periodically test Luxfer composite cylinders safely and effectively.Your system supplier or gas company should have provided you with instructions for the safeand proper filling of your composite cylinder. Carefully follow those instructions. Please bear inmind that you must also follow all applicable local and national regulations concerning filling,use, maintenance and periodic retesting and requalification of your composite cylinder.If you have questions about the design, development, qualification, manufacturing and testing ofyour cylinder, visit Luxfer’s website at www.luxfercylinders.com or call Luxfer CustomerService in Riverside, California U.S.A. at 800-764-0366.Copyright 2008 By Luxfer Inc. All rights reserved.Except as permitted under the U.S. Copyright Act of 1976,no part of this book may be reproduced in any form withoutthe express written consent of Luxfer Inc.Published in the U.S.A. by Luxfer Inc.3016 Kansas AvenueRiverside, CA 92507 USATelephone: 951-684-5110www.luxfercylinders.com3
Luxfer: Setting the Standard WorldwideFounded in 1898, Luxfer is the world’s largest manufacturer of high-pressure aluminum andcomposite cylinders with manufacturing facilities and sales offices around the world. Theindustry leader in research and development and innovation, Luxfer holds numerous globalpatents related to cylinder and metallurgical technology.As the world’s leading manufacturer of high-pressure composite cylinders, Luxfer strivescontinually to improve the quality and performance of its products. The following are some ofthe improvements and innovations that Luxfer has introduced for carbon composite cylinders:1993 – Smooth gel-coat finish. Fully wrapped composite cylinders were sold with a roughexternal surface until Luxfer introduced the gel-coat finish for carbon composite cylinders.This smooth, attractive finish, which resists dirt and damage and makes cleaning much easier, seta new standard for composite cylinder aesthetics.1995 – Luxfer was the first company to be granted approval for sale of its carbon-fibercomposite cylinders in the USA and Canada.2001 – First approval for a five-year requalification period in the USA and Canada.2003 – First European five-year requalification interval for cylinders with the CE mark for use inthe European Union.2005 – First carbon fiber cylinders manufactured in Luxfer China, Shanghai and Luxfer France,Gerzat.2007 – Approval of non-metallic protective caps for use in the USA and Canada.2008 – Introduction of three new composite cylinder ranges to the USA:LCX–SL – Super-Lightweight cylinders, the lightest carbon composite cylinders forSCBA and emergency use.LCX–XD – Carbon cylinders with reinforced domes for extra damage resistance inextreme duty.LCX–EL – Carbon cylinders designed for service life of up to 30 years.4
1. Cylinder design and specificationsA Luxfer fully wrapped, carbon composite cylinder is composed of these basic components: An ultra-lightweight, thin-walled, seamless aluminum liner with no leak paths or joints.Luxfer manufactures its own liners from aluminum alloy 6061 (AA6061). Liners receivea external coating to prevent the possibility of corrosion underneath the compositewrapping. Each liner is overwrapped with carbon fiber in an epoxy matrix using computercontrolled winding machines. A layer of glass fiber is wound onto the carbon as a sacrificial impact and abrasion layer,and a label is applied under the last layers of glass to protect it from damage. Ultra thin-walled aluminum liner Smooth, inert, corrosion-resistant internal finish Insulating layer between liner and overwrap High-performance carbon-fiber overwrap in epoxy resin matrix High-strength fiberglass-reinforced plastic (FRP) protective layer with smooth gel coat Precision-machined thread5
In the U.S.A. and Canada, Luxfer offers three different carbon composite cylinder ranges with a15-year design life.LCX Introduced in 1997, this standard range of carbon composite cylinders offers a balance of highstrength and light weight for storage of gases at high pressure.LCX–SL These cylinders have the same fundamental design as the standard LCX range, but are lighterdue to reductions in the weight of the aluminum liner and optimization of the carbon compositereinforcement. The SL range has the same thickness of glass overwrap as the standard carboncylinders, so you can use the same inspection criteria for both.LCX–XD The new range of XD “Extreme Duty” carbon cylinders have the same liners and carboncomposite reinforcement as the standard LCX range, but have extra glass reinforcement on thecylinder domes to increase damage resistance.Visit the Luxfer website at www.luxfercylinders.com for additional information about thecomplete range of Luxfer cylinders.6
1.1 Special PermitsU.S. Department of Transportation (DOT) Special Permit DOT SP 10915DOT SP 10915 authorizes the sale and use of non-DOT specification fully wrapped carbonfiber-reinforced aluminum cylinders with a 15-year design life for use in the U.S.A. Thisincludes the Luxfer LCX, LCX-SL and LCX-XD brands of cylinders.These cylinders are designed and tested in accordance with the “Basic Requirements for FullyWrapped Carbon-Fiber Reinforced Aluminum Lined Cylinders” (DOT-CFFC). The products areauthorized for the transportation of compressed gases named in the permit. Cylindersmanufactured under DOT Special Permit may not be used for underwater breathing purposes.A copy of the Luxfer DOT permits can be obtained from Luxfer or from the DOT HazardousMaterials website at http://hazmat.dot.gov/.The marked service pressure may not exceed 5,000 psi (34,474 kPa) at a reference temperatureof 70o F (21.1 C). The test pressure is 5/3 times the design service pressure. The cylinder musthave a minimum safety factor (burst/service-pressure ratio) of 3.4. Water volume may notexceed 91 liters (200 lb).Requalification (retest) period—A five-year requalification (retest) interval is permitted forLuxfer carbon cylinders manufactured and approved to DOT Special Permit SP10915.Cylinder life—The currently approved life for Luxfer carbon composite cylinders is 15 yearsfrom the date of manufacture.Transport Canada (TC) Special PermitCylinder design and testing is conducted in accordance with the standard CAN/CSA B339.Luxfer carbon cylinders for use in Canada are manufactured in accordance with TransportCanada Permit for Equivalent Level of Safety SU 5134, which authorizes the sale and use offully wrapped carbon-fiber-reinforced aluminum cylinders transportation of compressed gasesnamed in the permit. SU 5134 authorizes cylinders with a 15-year design life, which include theLuxfer LCX, SL and XD ranges of cylinders.A copy of the Luxfer TC permit can be obtained from Luxfer or from the Transport Canada website on Transport of Dangerous Goods (http://www.tc.gc.ca/tdg/permits/menu.htm). The markedservice pressure may not exceed 5,000 psi (34,474 kPa) at a reference temperature of 70o F(21.1 C). The test pressure is 3/2 times the design service pressure. The cylinder must have aminimum safety factor (burst/service-pressure ratio) of 3.4.Requalification (retest) period—A five-year requalification (retest) interval is permitted forLuxfer carbon cylinders manufactured and approved to TC SU 5134.7
2. Design and performance criteria2.1 Design criteriaThe design thickness of the fiber overwrapping cannot be reduced to a simple formula because ofvarying load-bearing layers and varying orientations and thicknesses of composite layers.Moreover, when these components, with their different strength and stiffness characteristics, arepre-strained in the autofrettage process, a complex distribution of stress results. This is analyzedusing finite element analysis computer techniques. All cylinders are manufactured by computercontrolled fiber-winding machines to ensure correct lay-up and high integrity of the overwrap.Luxfer uses a variety of computer analysis techniques, including finite element analysis, toproduce a reliable model of the cylinder and to calculate the maximum stress at any point in theliner and fibers. Also calculated are load distribution between liner and fibers at zero pressure,service pressure, test pressure and burst pressure. The model used to analyze the cylinder bodytakes into consideration non-linear material behavior and non-linear geometric changes,accounting both for circumferential and longitudinal pressure stresses.Note: Maximum stresses in the cylinder ends are always designed to be less than the maximumstresses in the cylinder body to pass burst tests. The maximum calculated tensile stress in anyfibers (carbon or glass) must not exceed 30 percent of the fiber stress corresponding to theminimum required burst pressure.Cylinder openings:(i) Openings are permitted on heads only. The centerline of the openings must coincide with thecenterline of the cylinder.(ii) Threads must be clean-cut, even, without checks, and must be designed in compliance withthe requirements of the Federal Standard FED-STDH28.(iii) Tapered threads are not permitted in CFFC cylinders(iv) Straight threads having at least six threads must have a calculated factor of safety in shearof at least 10 at the test pressure for the cylinder.3.2 Qualification testingIt is not possible to use finite-element modeling techniques accurately for all differentenvironments to which a gas cylinder might be exposed. To ensure the safe application of the8
cylinder design, a testing program is necessary to prove performance in the anticipated serviceenvironment.The following tests are conducted on the cylinder materials and composite overwrap: Strength of the carbon fibers Strength of the glass fibers Interlaminar shear strength of the composite Flexural strength of the compositeThe following tests are conducted on finished cylinders: Extreme temperature fluctuation: -58ºF (-50ºC) to 140ºF ( 60ºC) Impact resistance High-velocity impact resistance Environmental exposure at high temperatures and high humidity Exposure to fire Cylinder ultimate strength (burst test) Cyclic fatigue performance9
3. Manufacture3.1 Aluminum-alloy linersLuxfer manufactures liners from 6061-alloy (AA6061) aluminum plate. Each liner is colddrawn to thickness and hot-spun closed on the open end. The liner is then subjected to a solutionheat treatment and artificial aging process to develop strength and toughness required for “T6”mechanical properties.The liner neck is then machined for threads and port seal surfaces.3.2 Inspection proceduresRaw materials are checked and identified on receipt. Liners are checked for wall thickness,straightness, out-of-roundness, eccentricity and surface finish. The effectiveness of the heattreatment is verified by conducting tensile tests on a sample liner from a heat-treatment lot.The thread for every liner is verified.Liners are inspected by lot according to DOT-CFFC and CAN/CSA B-339. Additional visualchecks are conducted on liners prior to wrapping to ensure they are clean, free from surfacedefects and manufactured to the design drawing.10
3.3 Composite overwrappingComposite overwrapping, pressure testing and finishing operations are carried out at Luxfer GasCylinders in Riverside, California U.S.A.Reinforcing carbon fiber in an epoxy matrix contributes most of the strength of full-wrap carboncomposite cylinders. Fibers are impregnated with epoxy resin and applied to the liner bycomputer-controlled filament-winding machines that ensure correct placement of each fiber. Thecylinder is then overwrapped with layers of fiberglass, and an identification label is appliedunder the last layer of glass. The purpose of the outer layer of glass fiber is to protect the cylinderfrom damage. The net load-sharing capability or this layer is not considered part of the totalpressure load in the cylinder at minimum required burst pressure.Composite resin is cured using appropriate controlled-temperature profiles to ensure intimatecontact between the fiber filaments and the resin system, as well as complete curing of the resinmatrix.After the resin is cured, cylinders undergo autofrettage to redistribute the stresses within thealuminum and composite overwrap. Autofrettage is a pressurization process at a designatedpressure in excess of test pressure, and at this stress level the yield point of aluminum isexceeded—that is, the aluminum deforms plastically. When the pressure returns to zero, thealuminum is in compression and the carbon and glass fiber composite is in tension. Therefore, atnormal working pressure, the developed stresses in the aluminum liner are reduced compared tothose found in a standard aluminum cylinder. Luxfer applies a gel-coat finish on top of the glassfiber layers, creating an easy-to-clean, smooth surface that is extremely resilient. The gel-coatresists abrasion, impact and UV degradation.3.4 Cylinder lot inspection and testingThe maximum composite cylinder lot (or batch) size is 200 units, plus the number of cylindersrequired for destructive testing, in accordance with DOT-CFFC and CAN/CSA B339.Each lot of composite cylinders is examined to ensure compliance with design specifications.The following final inspections are carried out in accordance with Luxfer’s Quality Assuranceprocedures:a) Visual inspection100 % (all cylinders)b) Dimensional check10 % or to customer requirementsc) Weight check100 %d) Water-capacity check100 %e) Compliance of marking100%.For b), if one unacceptable cylinder is found, then all cylinders in the lot are inspected.The following performance tests are conducted:11
Hydrostatic test—Each cylinder is hydrostatically pressurized to test pressure after the cylinderhas been autofrettaged. Test pressure is maintained for a minimum of 60 seconds and as muchlonger as necessary to ensure stable volumetric expansion. The elastic and total volumetricexpansions are determined. Cylinders that show evidence of leakage or distortion are rejected.The water-jacket method is used to conduct the hydrostatic test in the U.S.A. and Canada.The pressure reading should be accurate within one percent in the range of 80 percent to 120percent of the test pressure, and the volumetric expansion measurement should be accurate towithin one percent of the total expansion established when in system calibration, or 0.1 cubiccentimeter. Records are maintained as evidence of the equipment calibration.Hydraulic burst test—This test is conducted on one cylinder per lot. The cylinder is pressurizedat a uniform rate up to 3.4 times the service pressure and held at that pressure for a minimum of60 seconds. Then the pressure is increased until the cylinder fails, and the pressure is recorded atthe onset of failure.Pressure cycling test—This test is conducted on one cylinder per lot. The cylinder is subjectedto a minimum of 10,000 cycles to service pressure followed by a further 30 cycles to testpressure.Each test cylinder must withstand the cycling pressurization test without evidence of visuallyobservable damage, distortion or leakage. After successfully passing the cycling test, each testcylinder is burst-tested and must demonstrate a minimum burst pressure of 3.06 times servicepressure.3.5 Independent inspection authoritiesThe independent inspection authority used by Luxfer in the manufacture of composite cylindersin the U.S.A. is:Arrowhead Industrial Services, Inc. (AISI)3537 South NC Hwy 119P.O. Box 1000Graham, NC 27253 USA3.6 Marking and labelingEach finished composite cylinder has a label incorporated into the fiberglass overwrap. The labelcontains the following information: DOT Special Permit (SP) number or DOT Exemption (E) numberfollowed by service pressure expressed in pounds per square inchgauge (psig) and, if applicable, Transport Canada Permit numberfollowed by service pressure expressed in bar.12
A serial number and the manufacturer’s name, identification numberor symbol (registered at the Associate Administrator for HazardousMaterials safety), located just below or immediately following theDOT marking above. The independent inspection agency (IIA) official mark, which must beplaced near the serial number. The marking must contain date (monthand year) of the initial hydrostatic test for that cylinder. Rejection elastic expansion (REE) marking in cubic centimeters.Label illegibility may be cause for rejecting a cylinder. If the serial number is no longer legible,the cylinder must be condemned.A Luxfer composite cylinder that still has a legible serial number can be returned to service onlyafter all other product information is made legible. For instance, an illegible part of a compositeSCBA cylinder label that still has a legible serial number can be corrected by putting requiredinformation back on the cylinder, but only Luxfer can perform this process. Contact Luxfer forfurther information, if needed. Sample labels are included as Appendix 1.3.7 Protective end caps and bootsLuxfer offers protective end caps and boots for use on cylinders to increase resistance toabrasion, cuts and other damage. Manufactured from a fire-retardant polymer, the caps and bootshave been shown to pass all tests to NIOSH and NFPA regulations.Since caps and boots are not integral parts of the cylinder, they must be removed atrequalification (retest). Attached to the cylinder with Loctite E-05CL Hysol EpoxyAdhesive, but can be removed and reinstalled by following the procedure detailed in Appendix 2.Loctite E-05CL is a toughened, ultra-clear, fast-setting, high-peel, low-odor epoxy with a fiveminute work-life.13
Luxfer cylinder fitted with protective cap and boot.4. Cylinder use4.1. GeneralFollow these general guidelines to ensure safe, proper use.Maintenance of Carbon Composite Cylinders.No regularly scheduled maintenance is required apart from periodic requalification (retest).Visually inspect each cylinder before filling for signs of damage (see Section 5.2).If desired, clean the cylinder using fresh tap water alone or water and a mild detergent, ifnecessary. If a detergent is used, rinse the cylinder thoroughly with clean water. Thoroughly dryall components before reassembly. Do not apply heat.Short-term storage (less than six months)—Tightly close the cylinder valve. Leave pressurebetween 30 and 40 psi (about 2 and 3 bar) in the cylinder. Secure the cylinder and assembly to14
prevent the cylinder from rolling loose, tipping over or falling. Store at room temperature in adry place, away from chemicals, artificial heat sources and corrosive environments.Long-term storage—If it becomes necessary to store a cylinder for a prolonged period, thefollowing procedure is recommended. Empty the cylinder and remove the valve. Wash thecylinder internally and externally with fresh tap water, rinse with distilled or de-ionized waterand then thoroughly dry the cylinder inside and out. Visually inspect the internal surfaces. Installthe valve and O-ring according to the SCBA manufacturer’s recommendations. The valvedcylinder should have between 30 and 40 psi (about 2 to 3 bar) of positive pressure inside thecylinder valve assembly. Protect the valve from possible damage. Store the cylinder eitherupright or horizontally at room temperature in dry conditions away from chemicals, artificialheat sources and corrosive environments.Handling—Do not drag, drop or roughly handle cylinders. When transporting cylinders, ensurethat the valve is protected from damage and that the cylinder is well secured. Cylinders shouldnot be allowed to roll around loose, tip or fall during transport. Secure cylinders in a protectedposition, and do not allow other cargo to strike or damage cylinders.Painting—Never use corrosive, caustic or acid paint strippers, burning techniques or solvents toremove paint from composite cylinder surfaces or to prepare those surfaces for painting. Retouchdamaged paint areas with air-drying paint. Never heat a cylinder to dry or cure paint.If cylinder composite materials or metal are damaged, do not paint over the damage. Have thecylinder inspected by an authorized technician. It should not be necessary to paint an entirecomposite cylinder. In the unlikely event that overall painting is required, contact Luxfer forrecommendations.4.2 Approved gasesLuxfer carbon composite cylinders are approved for use with the following gases:Gas nameAir, compressed (containing up to 39% by volume oxygencontent)Argon, compressedCarbon DioxideCompressed gas, n.o.s.Compressed gas, oxidizing, n.o.s.Helium, compressedHydrogen, compressedLiquefied gas, n.o.s.Methane, compressed or Natural gas, compressed (with highmethane N3156UN1046UN1049UN3163UN197115
Nitrogen, compressedNitrous OxideOxygen, compressed2.22.22.2UN1066UN1070UN10724.3 Cylinder fillingThe pressure of a filled cylinder must not exceed the design filling pressure indicated on thecylinder label.Composite material used in the manufacture of the cylinder is a good insulator, and so heatgenerated by the filling process takes longer to dissipate than with traditional metal cylinders.Consequently, a cylinder charged to normal filling pressure will reach temperatures in excess of120oF (49 C) during filling, particularly if filled quickly. (Note: This temperature is well belowany temperature that might degrade the aluminum or the composite material.) Then, on returningto ambient temperature, the pressure inside the cylinder will drop slightly, and the cylinder willnot have a full charge. Topping up will be necessary to achieve a full charge.However, it is also possible to optimize filling procedures (e.g., by varying the speed of filling)to achieve a full charge.Slow filling—Filling a cylinder slowly will significantly reduce the heat generated in the fillingprocess. A maximum charging rate of 435 psi/min (30 bar/min) or less is recommended.Fast filling—A Luxfer composite cylinder can be fast-filled and reused if the cylinder isproperly handled, well maintained and undamaged. However, the filler should take care not toexceed the maximum service pressure.Compressed air—When filling composite cylinders with compressed air, always ensure that thecompressor has been properly maintained so that the air quality complies with the appropriatestandard.Maximum moisture content should conform to recommendations in Compressed GasAssociation (CGA) G-7. In uncontrolled conditions during which moisture may have entered thecylinder, internally inspect the cylinder at least every six months. Do not apply heat. Ifcontaminants are found inside the cylinder, the cylinder interior must be cleaned and driedfollowing procedures found in Section 8.1 of this manual.Oxygen—Use only cylinders, valves and other components specifically cleaned for oxygen oroxygen-enriched applications. (Breathing air that contains more than 23.5 percent oxygen isgenerally referred to as "oxygen-enriched air.") Use only lubricants approved for oxygen andoxygen-enriched applications. Non-approved lubricants, especially those containinghydrocarbons, could react with oxygen and cause a fire.The cylinder interior, valve threads, O-ring and any equipment coming into contact with oxygenmust be cleaned for oxygen and oxygen-enriched use and be free of any contaminants that mightreact with oxygen. For additional information about the use of oxygen and oxygen-enriched gasmixtures, contact Luxfer or the oxygen equipment manufacturer.16
5. Periodic inspection and requalification5.1 GeneralLuxfer cylinders must be subjected to a thorough periodic
Cylinder life—The currently approved life for Luxfer carbon composite cylinders is 15 years from the date of manufacture. Transport Canada (TC) Special Permit Cylinder design and testing is conducted in accordance with the standard CAN/CSA B339. Luxfer carbon cylinders for us
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