Asme Sec x (Rf-fab Rqts)

PART RFFABRICATION REQUIREMENTS

Article RF-1 General Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Article RF-2 Special Fabrication Requirements for Bag-Molding Process(for Class I Vessels Only). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Article RF-3 Special Fabrication Requirements for Centrifugal-Casting Process(for Class I Vessels Only). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

Article RF-4 Special Fabrication Requirements for Filament-Winding Process(Classes I and II). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Article RF-5 Special Fabrication Requirements for Contact-Molding Process(Classes I and II). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Article RF-6 Special Fabrication Requirements for Matched Molded Heads (Used forClosures for Centrifugally Cast Vessels — for Class I Vessels Only) . . . 79

Article RF-7 Special Fabrication Requirements for Joining Components. . . . . . . . . . . . . . 81

Figures

RF-210.1 Fiber Side Wall Lay-Up for Bag Molding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

RF-210.2 Head or End Preform for Cylindrical Vessel. . . . . . . . . . . . . . . . . . . . . . . . . . 72

RF-610.1 Fiber Preform and Insert for Head for Centrifugally Cast Vessel. . . . . . . . . 80

RF-610.2 Fiber Head or End Preformed Inserts for Centrifugally Cast VesselHeads. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

69

COPYRIGHT American Society of Mechanical EngineersLicensed by Information Handling ServicesCOPYRIGHT American Society of Mechanical EngineersLicensed by Information Handling Services

ARTICLE RF-1GENERAL REQUIREMENTS

RF-100 SCOPE

This Part provides rules governing the fabrication offiber-reinforced plastic pressure vessels. The fabricationprocesses are limited to the bag-molding, centrifugal-casting, contact-molding, and filament-winding pro-cesses for Class I vessels, and limited to contact moldingand filament winding for Class II vessels.

RF-110 PROCEDURE SPECIFICATIONS

(a) For every combination of fabrication method,Design Specification, and material variation employedin fabricating vessels to be marked with the Codesymbol, the Fabricator shall prepare a Procedure Speci-fication which shall be qualified in accordance withPart RQ of this Section before it is used to fabricatevessels to be so marked.

(b) Any essential variation from the Procedure Speci-fication for Class I vessels (see RQ-200, RQ-300, RQ-400, and RQ-500) shall require that the ProcedureSpecification be rewritten and requalified before being

70

used to fabricate vessels to be marked with the Codesymbol.

(c) The Procedure Specification for Class II vessels(Form Q-120) requires that the Fabricator establish thedesign of the vessel in accordance with Article RD-11 based on the elastic and strength constants for thespecific combinations of fiber, resin, ply sequence, andply orientations used for the vessel laminate. Anyvariation in materials used to fabricate the vessel orvessel part from those materials used to determine theelastic and strength constants upon which the DesignCalculations were based shall require that new elasticconstants be obtained and new Design Calculationsmade. Any variation in the ply sequence or ply orienta-tion made in the fabrication of the vessel or vesselpart that differs from the ply sequence and orientationspecified in the Procedure Specification and upon whichthe Design Calculations were based shall require thatnew calculations be made.

The new calculations must satisfy the User’s DesignSpecification and the requirements of this Section. TheProcedure Specification shall be amended to reflect theactual fabrication and the Design Report amended toreflect the design basis.


ARTICLE RF-2SPECIAL FABRICATION REQUIREMENTS

FOR BAG-MOLDING PROCESS(FOR CLASS I VESSELS ONLY)

RF-200 FIBER CONTENT

The composite structure shall consist of random shortlength1 fiber filaments in a resin matrix. The weightof the fiber reinforcement shall conform to that setforth in the Procedure Specification (see Form Q-106)within a tolerance of +20% and −0%. Supplementarypads used to give greater wall thickness at openingsand attachments shall have a fiber content not less than35% by weight.

RF-201 Fiber Composition

One or more of the fiber types stipulated in RM-110 and specified in the Procedure Specification shallbe used for reinforcement.

RF-210 FORM OF FIBERREINFORCEMENT

(a) The fiber reinforcement shall consist of mats orpreforms made from chopped fiber strands. The percent-age of resin binder shall not exceed 10% by weightin mat or preform.

(b) The flat mats for cylindrical reinforcement shallbe laid up in a staggered pattern and rolled on amandrel prior to assembly into the mold (see Fig. RF-210.1).

(c) The head or end preforms shall be made bydepositing chopped fiber from an airstream with oneof the resin systems specified in RM-120 dispersed inthe fiber (see Fig. RF-210.2).

1 Random short length is that produced by cutter blades with notless than 1 in. (25 mm) nor more than 4 in. (102 mm) spacing.

71

FIG. RF-210.1 FIBER SIDE WALL LAY-UPFOR BAG MOLDING

RF-211 Resin System

The resin system shall be one of the resin systemsspecified in RM-120 and as required for the particularservice conditions specified in the Design Specificationand by the qualified Procedure Specification. No filler,pigment, or dye additions shall be used which willinterfere with the natural color of the resin except aspermitted by the Procedure Specification.

RF-212 Cure

If other than ambient temperature cure is required,the design and operation of the curing equipment shallassure uniform heating over the entire surface of thepressure vessel and vessel parts. The curing time and


RF-212 2001 SECTION X RF-250

FIG. RF-210.2 HEAD OR END PREFORMFOR CYLINDRICAL VESSEL

temperature shall conform to those stipulated in thequalified Procedure Specification (see Form Q-106).

RF-220 MOLDS

RF-221 Mold Material

The molds for pressure bag molding of pressurevessels and vessel parts may be fabricated of anymaterial or combination of materials. The molds shallhave sufficient dimensional stability to withstand thebag pressure loads during the forming and cure cycles.

RF-222 Mold Release Agent

The surface of the mold in contact with the vesselor vessel part shall be treated with a suitable releaseagent to facilitate removal of the vessel or part fromthe mold. Such release agent shall not be detrimentalto the vessel or part.

72

RF-223 Mold Removal

The mold may be removed from the vessel, or viceversa, by any technique which will not damage thevessel.

RF-224 Pressure Bags

The pressure bags used to compress the fiber rein-forcement mats and preforms and to hold the fiber andresin in position during the curing cycle may be madeof any flexible material that the molding resin will notattack, or which can be protected from such attack bya suitable material.

RF-230 LINERS

RF-231 Liner Material

Liners, when used, may be made of elastomeric orplastic material. When such liner materials are used,the liner may be used as the pressure bag. Alternatively,liners may be applied to the completed vessel.

RF-232 Provisions in Liners for Openings inVessels

Liners shall be designed so that they extend com-pletely through all access openings in the vessel.

RF-240 OPENINGS IN VESSELS

The number, size, and location of openings in bag-molded vessels shall meet the requirements of theDesign Specification. The adequacy of reinforcement,if any, for such openings shall be determined by thetest and design criteria required by RD-160 to provedesign adequacy.

RF-250 MOLDED-IN FITTINGS

Openings less than NPS 11⁄2 (DN 40) may be fabri-cated by molding around a removable insert form,provided the molding operation is detailed in the Proce-dure Specification and subsequent proof of design ade-quacy is demonstrated in accordance with RD-160.


ARTICLE RF-3SPECIAL FABRICATIONREQUIREMENTS FOR

CENTRIFUGAL-CASTING PROCESS(FOR CLASS I VESSELS ONLY)




One or more of the fiber types conforming to thecomposition stipulated in RM-110 and specified in theProcedure Specification shall be used for reinforcement.

RF-310 FORM OF REINFORCEMENT

The fiber reinforcement for centrifugally cast cylin-ders shall consist of chopped fiber strands or rovings.Fabrication of heads shall conform to RF-210(c).

RF-311 Resin System

The resin system shall be one of the resin systemsspecified in RM-120 and as required for the particularservice conditions specified in the Design Specificationand by the Procedure Specification. No filler, pigment,or dye additions shall be used which will interfere withthe natural color of the resin except as permitted bythe Procedure Specification.


73

RF-312 Cure

If other than ambient temperature cure is employed,the design and operation of the curing equipment shallassure uniform heating over the entire cylinder. Thecuring times and temperatures shall conform to thosestipulated in the qualified Procedure Specification (seeForm Q-106).

RF-320 MANDRELS

RF-321 Mandrel Material

The mandrel shall be fabricated of any materialor combination of materials of sufficient rigidity anddimensional stability to withstand the centrifugal-castingloads and the curing cycle.

RF-322 Mandrel Release Agent

The mandrel shall be treated with a suitable releaseagent to facilitate removal of the cured cylinder. Suchrelease agent shall not be detrimental to the cylinder.

RF-323 Mandrel Removal

The cylinder may be removed from the mandrel, orvice versa, by any technique which will not damagethe cylinder.

RF-324 Matched-Die-Molded Heads

Matched-die-molded heads used as closures for cen-trifugally cast cylinders shall be fabricated in accordancewith the requirements of Article RF-6.



RF-330 LINERS


Liners, when used, may be made of elastomericor plastic material. The liner may be applied to thecentrifugally cast cylinder after its heads are attachedby adhesive bonding.

RF-332 Provisions in Liners for VesselOpenings



The number, size, and location of openings in centrif-ugally cast cylinders and attached heads shall meet therequirements of the User’s Design Specification andthis Section. The adequacy of reinforcement, if any,for such openings shall be determined by the testsrequired by RD-160 to prove design adequacy.

74



FILAMENT-WINDING PROCESS(CLASSES I AND II)


The composite structure shall consist of fiber strandsin a resin matrix. The weight of the fiber reinforcementshall conform to that set forth in the Procedure Specifi-cation (see Form Q-107 for Class I vessels and FormQ-120 for Class II vessels) with a tolerance of +10%and −0%.

RF-400.1 Fiber Content in Supplementary Pads.Supplementary pads used to give greater wall thicknessat openings and attachments shall have a fiber contentnot less than 35% by weight.


One or more of the fiber types conforming to thecomposition stipulated in RM-110 and specified in theProcedure Specification shall be used for reinforcementof filament-wound pressure vessels.

RF-410 FORM OF REINFORCEMENT

RF-410.1 Patterns.Specific winding patterns for thecontinuous fiber strands shall be used as defined inthe qualified Procedure Specification (see Form Q-107for Class I vessels and Form Q-120 for Class II vessels).Any winding pattern which places the filaments in thedesired orientation and is designated in the ProcedureSpecification may be used.

RF-410.2 Alignment With Stresses.In general, thepatterns shall be so arranged that the stressed filamentsare aligned to resist the principal stresses which resultfrom internal pressure and other loadings.

RF-410.3 Wall Thickness. The wall thickness isgoverned by the number of layers of wound strands

75

of filaments specified in the Procedure Specificationfor the particular vessel.

RF-411 Resin System

The resin system shall be one of the resin systemsspecified in RM-120 and as required for the particularservice conditions specified by the Design Specificationand qualified Procedure Specification. No filler, pigment,or dye additions shall be used which will interfere withthe natural color of the resin except as permitted bythe Procedure Specification.

RF-412 Cure

If other than ambient temperature cure is employed,the design and operation of the curing equipment shallprovide uniform heating over the entire surface of thevessel. Heating may be done from the inside or outsideof the pressure vessel or from both inside and outside.The cure times and temperatures shall conform to thosestipulated in the qualified Procedure Specification (seeForm Q-107 for Class I vessels and Form Q-120 forClass II vessels).

RF-413 Filament Winding

(a) Tensioning.Tension on the strands of filamentsduring the winding operation shall be controlled toassure uniformly stressed filaments in the compositewall.

(b) Winding Speed.The speed of winding shall belimited only by the ability to meet the tensioningrequirements, to conform to the specified winding pat-tern, and to assure adequate resin impregnation.



(c) Bandwidth and Spacing. The bandwidth and spac-ing shall conform to those specified in the qualifiedProcedure Specification.

RF-420 MANDRELS

RF-421 Mandrel Material

The mandrel may be fabricated of any material orcombination of materials with sufficient rigidity anddimensional stability to resist the winding loads andthe compressive loads on the mandrel which occurduring the cure cycle.

RF-422 Mandrel Release Agent

The mandrel, if removed, may be treated with asuitable release agent to facilitate its removal from thecured pressure vessel. Such release agent shall not bedetrimental to the finished vessel.

RF-423 Mandrel Removal

The mandrel shall be removed by any techniquewhich will not damage the filament-wound compositeor the liner, if one is present.

RF-430 LINERS


Liners, when used, may be made of elastomeric,plastic, or metallic materials. The liner may be appliedto the mandrel prior to the start of the winding operation.

(a) If applied to the mandrel before the windingoperation begins, the thickness and hardness of theliner material shall be such that the filament orientation

76

and tension will not be adversely affected by deflectionor “flow” of the liner material.

(b) Alternatively, the liner may be applied to thecompleted filament-wound pressure vessel, in whichcase the restrictions on thickness and hardness do notapply.

(c) If the liner is required to be bonded to thefilament-wound composite, the outer liner surface shallbe treated to facilitate such bonding.

(d) The design of metallic liners shall take intoaccount the pronounced difference in the modulus ofelasticity of the laminate and the metallic liner.

(e) For vessels used for potable water, as describedin RG-113 (Section IV Application), the liner materialsmay be those listed in HLW-200, Section IV or shallbe suitable for potable water applications as demon-strated by approval of the material by the NationalSanitation Foundation (NSF) in accordance with NSFStandard 14.

RF-432 Provisions in Liners for VesselOpenings



The number, size, and location of openings in fila-ment-wound pressure vessels classified by RG-404.1shall meet the requirements of the User’s Design Speci-fication. The adequacy of reinforcement, if any, forsuch openings shall be determined by the tests requiredby RD-160 to prove design adequacy for Class I vessels.For Class II vessels the reinforcement must conformto the design criteria of Article RD-11 and acceptancetesting criteria of Article RT-6.



CONTACT-MOLDING PROCESS(CLASSES I AND II)


The composite structure shall consist of random shortlength1 fiber filaments and roving (or biaxial fabric,singular or in combination) in a resin matrix. Theweight of the fiber reinforcement shall conform to thatset forth in the Procedure Specification (see Form Q-108 for Class I vessels and Form Q-120 for ClassII vessels) within a tolerance of +10% and −0%.Supplementary pads used to give greater wall thicknessat openings and attachments shall have a fiber contentnot less than 35% by weight.


One of the fiber types conforming to the compositionstipulated in RM-110 and as specified in the ProcedureSpecification shall be used for reinforcement.


(a) The fiber reinforcement shall consist of randomshort length fiber filaments and roving (or biaxialfabrics) as specified in RF-501.

(b) Flat mats for cylindrical reinforcement shall belaid up as separate layers and overlapped in a staggeredpattern. Resin shall be applied to each layer in sucha manner as to wet out completely.

(c) On cylindrical components, the orientation of thewarp and weft fiber stands of woven roving (or biaxialfabrics) shall be defined with respect to the circumferen-


77

tial (hoop) and longitudinal (axial) axis of the cylindricalcomponent.

(d) On elliptical or hemispherical shapes, the orienta-tion of the warp and weft fiber stands of woven roving(or biaxial fabrics) shall be defined with respect to themeridional and circumferential axis.

RF-511 Resin System

The resin system shall be one or more of the resinsspecified in RM-120 and as required for the particularservice conditions specified in the Design Specificationand by the qualified Procedure Specification. No filler,pigment, or dye additions shall be used which willinterfere with the natural color of the resin except aspermitted by the Procedure Specification.

RF-512 Cure

The cure procedure and post cure if required shallconform to those stipulated in the qualified ProcedureSpecification (see Form Q-108 for Class I vessels andForm Q-120 for Class II vessels).

RF-520 MOLDS


The molds for contact molding of pressure vesselsmay be fabricated of any material or combination ofmaterials. The molds shall have sufficient dimensionalstability to withstand the contact-molding operation andcure or post cure procedures.




The surface of the mold in contact with the vesselshall be treated with a suitable release agent to facilitateremoval from the mold. Such release agent shall notbe detrimental to the finished vessel.

RF-523 Mold Removal

The mold may be removed from the vessel, or viceversa, by any technique which will not damage thevessel.

RF-530 LINERS


Liners, when used, may be made of either thermosetor thermoplastic materials.

78

RF-532 Provisions in Liners for Openings inVessels



The number, size, and location of openings in contact-molded vessels shall meet the requirements of the User’sDesign Specification. The adequacy of reinforcement, ifany, for such openings shall be determined by the testsrequired by RD-160 to prove design adequacy for ClassI vessels. For Class II vessels the reinforcement mustconform to the design criteria of Article RD-11 andthe acceptance criteria of Article RT-6.


ARTICLE RF-6SPECIAL FABRICATION REQUIREMENTS

FOR MATCHED MOLDED HEADS(USED FOR CLOSURES FOR

CENTRIFUGALLY CAST VESSELS —FOR CLASS I VESSELS ONLY)

RF-600 CONTENT



One or more of the fiber types conforming to thecomposition stipulated in RM-110 and as specified in theProcedure Specification shall be used for reinforcement.


(a) The fiber reinforcement shall consist of preformsor preforms and inserts made from chopped fiber strands.The percentage of resin shall not exceed 10% by weightin the preforms or inserts.

(b) Inserts, if used, shall be tapered to a featheredge to blend smoothly into the preform (see Fig. RF-610.1).

(c) The head or end preforms shall be made bydepositing chopped fibers from an airstream with asuitable resin binder dispersed in the fiber.


79

(d) The insert may consist of one or more preformsto obtain the required thickness. These inserts may ormay not be on the axis of the vessel, depending onport or opening requirements (see Fig. RF-610.2).

(e) Rings of continuous rovings molded into headsto reinforce holes are permissible.

RF-611 Resin System

The resin system shall be one of the resin systemsspecified in RM-120 and as required for the particularservice conditions specified in the Design Specificationand by the qualified Procedure Specification. No filler,pigment, or dye additions shall be used which willinterfere with the natural color of the resin except aspermitted by the Procedure Specification.

RF-612 Cure

If other than ambient temperature cure is employed,the design and operation of the curing equipment shallassure uniform heating over the entire surface of thehead. The curing times and temperatures shall conformto those stipulated in the qualified Procedure Specifica-tion (see Form Q-106).

RF-620 MOLDS

Heads used as closures for centrifugally cast vesselsmay be molded by either:

(a) matched molds in which both male and femaleare rigid and uniformly heated; or



FIG. RF-610.1 FIBER PREFORM AND INSERT FORHEAD FOR CENTRIFUGALLY CAST VESSEL

(b) matched molds in which the female mold isuniformly heated and the male mold is a pressure bag.


The molds may be fabricated of any material orcombination of materials. The molds shall have suffi-cient dimensional stability to withstand the pressureloads during the forming and cure cycles.


The surfaces of the mold in contact with the headshall be treated with suitable release agent to facilitateremoval of the head from the mold. Such release agentshall not be detrimental to the heads.

80

FIG. RF-610.2 FIBER HEAD OR END PREFORMEDINSERTS FOR CENTRIFUGALLY CAST VESSEL

HEADS

RF-623 Head Removal

The head may be removed from the mold by anytechnique which will not damage the head.

RF-624 Pressure Bags

A pressure bag used in lieu of the male mold tocompress the fiber preform assembly and hold the fiberand resin in position during the curing cycle may bemade of any flexible material that the molding resinwill not attack or which can be protected from suchattack by a suitable material.

RF-630 OPENINGS IN HEADS

The number, size, and location of openings in headsshall meet the requirements of the User’s Design Speci-fication. The adequacy of reinforcement, if any, forsuch openings shall be determined by the tests requiredby RD-160 to prove design adequacy.


ARTICLE RF-7SPECIAL FABRICATION REQUIREMENTS FOR

JOINING COMPONENTS

RF-700 PROCEDURE SPECIFICATIONSAND QUALIFICATIONS

(a) When the fabricating process includes joining ofparts such as heads, or when it is desired to join twoor more cylinders to produce a long shell, the ProcedureSpecification shall include full details of the joiningprocess. Any variation in the design of the joints beingbonded, outside of those inherent in the process offorming the surfaces to be bonded, and any variationin the method used as set forth in the ProcedureSpecification, shall require requalification of the designand the Procedure Specification.

(b) Longitudinal seams made by any joining methodare prohibited.

(c) Adhesive bonding of the type whereby matingforces of two parts are joined by a thin adhesive orglue joint is limited to Class I vessels (see Form Q-115).

(d) Joining of Class II vessel parts is limited tosecondary overlay bonding as described in ArticleRD-11.

81


Documents

Asme Sec x (Rf-fab Rqts)