1、 WORLDWIDE ENGINEERING STANDARDS Material Specification GMW14658 Double Wall Construction Steel Tubing Copyright 2012 General Motors Company All Rights Reserved February 2012 Originating Department: North American Engineering Standards Page 1 of 17 1 Scope 1.1 Material Description. This standard cov
2、ers double wall construction tubing wherein the two walls and the joints are copper brazed in a reducing atmosphere to produce tubing satisfactory for hydraulic brake lines, lubrication oil lines, vacuum lines, air brake lines, etc. There are requirements for the base metal, the optional coating mat
3、erials, and the coated tubing. These requirements are applicable to the product coming out of the tube mills and the coating application lines, which are sometimes separate facilities. This tubing is used in the production of customized parts and assemblies. It is recommended that those parts and as
4、semblies be validated for corrosion performance, conductivity and continuity, strength, appearance, and other critical properties unique to the particular application. 1.2 Symbols. Not applicable. 1.3 Typical Applications. Double wall steel tubing is typically used for automotive hydraulic brake lin
5、es. 1.4 Remarks. Double wall steel tubing should not be used for fuel lines because residual copper can contribute to the formation of sour gas. 1.5 Tubing Designation Code. It is recommended that the codes in Paragraph 3 be used on drawings and purchase orders to designate tubing type, outside diam
6、eter, wall thickness, and manufacturing process. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. ASTM A254 ASTM B750 ISO 6892-1 SAE J527 ASTM A875 ASTM E8 ISO 8493 2.2 GM Standards/Specifications. GM6277M GMW3286
7、 GMW14700 GMW15282 GMW2 GMW3356 GMW14729 GMW15487 GMW3059 GMW14124 GMW14829 GMW15891 2.3 Additional References. 9274079 GMPT-5-001 No. 2 Diesel GMPT-5-020-A Bio Diesel GMPT-6-006 TF2 Gasoline GMPT-6-019 Oxidized Gasoline GMPT-6-023 E85 Low pHe TMC003 Material Safety Data Sheet guidance documents (av
8、ailable at ). 3 Requirements 3.1 Properties. See Table 7 for summary. Basic tubing material shall be cold rolled mild steel strip to GMW2M-ST-S CR1 or CR2. Brazing material should be copper or copper alloy containing 93% Cu by mass. For technical reasons the minimum coating thickness in the joint ar
9、ea on the zinc plated types (ZP + ZM) shall be 5 m minimum. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14658 Copyright 2012 General
10、Motors Company All Rights Reserved February 2012 Page 2 of 17 GMW14658 (I/II/III) “I” = Outside diameter of as-brazed, millimeters (mm) “II” = Wall thickness, millimeters (mm) “III” = Manufacturing Process (*) (*) Process Abbreviations: A = Aluminum G = Zinc-aluminum-alloy Z = Electroplated Zinc E =
11、 Aluminum Rich Epoxy Paint M = Modified Epoxy Ester Paint N = Extruded Nylon 11 or 12 Y = Extruded Nylon 612 P = Polyvinyl Fluoride (PVF) Coating Example: GMW14658 (6.00/0.7/ZP) indicates double walled braze tubing, 6 mm Outside Diameter (OD), 0.7 mm wall thickness, protected from corrosion with a b
12、ase coating of a zinc plate followed with a Polyvinyl Fluoride (PVF) topcoat. 3.1.1 Mechanical Properties. The following requirements shall apply only to the more common type of steel tubing; brazed-as manufactured. Properties of other classes of tubing, such as work hardened tubing, shall be as spe
13、cified through special agreement between supplier and purchaser. Test pieces for mechanical test shall be taken at the end of the tube manufacturing process (after coiling, etc.,) without any additional cold working. All mechanical tests shall be performed at 23 C 5 C per ISO 6892-1 or ASTM E8. Prop
14、erty Minimum Requirements Tensile Strength Rm 300 MPa 0.2% Yield Strength Rp0.2 200 MPa Fracture Elongation A10 14% 3.1.2 Drift Expanding Test (ISO 8493) Tubing shall be capable of being expanded over a tapered mandrel having an angle 60 until the internal diameter at expanded end is increased 20% w
15、ithout cracking or showing flaws (ASTM A254 Paragraph 6.3). Prior to expansion test, tubing shall be cut off square, edge crowned, and deburred. It shall be held firmly and squarely in the die, and punch must be guided on the axis of the tubing. 3.1.3 Bending Test Tubing shall be capable of being be
16、nt on a centerline radius of three times the tubing outside diameter without undue reduction of area of flattering when suitable bending fixtures used. Using this formula, reduction of area shall be 6% for the diameters and wall thicknesses covered by this specification. 3.1.4 Static Burst Pressure.
17、 3.1.4.1 General Motors North America (GMNA), General Motors Latin America Africa Middle East (LAAM), General Motors Asia Pacific (GMAP). Unless otherwise specified, tubing shall be capable of withstanding the following internal static hydraulic pressure: Through 10.0 mm OD35 MPa Over 10.0 mm throug
18、h 16.0 mm OD.15 MPa 3.1.4.2 General Motors Europe (GME) unless otherwise specified, tubing shall be capable of withstanding the internal static hydraulic pressure as specified in Table 2 and Table 4. 3.2 Dimensions. Tubing shall conform to the dimensions and tolerances listed by the purchaser. 3.2.1
19、 Brazed Tubing. Nominal diameter and wall thickness shall conform per Figure 1, and those listed in SAE J527 and Table 6 for GMNA, GMLAAM, GMAP and those listed in Tables 2 and 4 for GME. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo repro
20、duction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14658 Copyright 2012 General Motors Company All Rights Reserved February 2012 Page 3 of 17 Figure 1: Dimensions for Diameter and Wall Thickness 3.2.2 Flared Ends. The pipe flare ends (inverted flare) s
21、hall conform to the Supplementary Requirements in ASTM A254, Section S1. Table 1: External Finish Codes and Requirements Finish Finish Code External Finish Description and Material Requirements Zinc-Aluminum Alloy +Aluminum Rich Epoxy Paint GE Hot dip zinc-aluminum alloy coating consisting of a 5% a
22、luminum-balanced zinc alloy per ASTM B750 with a coating mass of 50 g/m2 per ASTM A875, Section 8 and a thickness of 3 m minimum anywhere on the tube per Appendix A. The hot dip zinc-aluminum coating is then subsequently coated with an approved pretreatment process and an approved aluminum-rich epox
23、y coating. Film Thickness: The aluminum-rich epoxy paint of the GE finish shall have a minimum thickness of 3 m anywhere on the tube as measured by the procedures in Appendix A. Actual thickness of the coatings in the GE finish shall be monitored circumferentially and longitudinally for each tube li
24、ne. A sampling plan shall be referenced in the control plan. Zinc-Aluminum Alloy + Extruded Nylon 11 or 12 GN Zinc-aluminum alloy as described above followed by a conversion coating, an epoxy resin based primer, and a topcoat of Nylon 11 or 12. Appearance: The topcoat shall be uniform in color and f
25、ree from discontinuities such as flow lines, pin holes, craters, or abnormal roughness. The topcoat shall be black in color unless otherwise specified on the engineering drawing. Film Thickness: The epoxy primer shall be 0.3 m minimum and the Nylon 11 or 12 topcoat shall have a minimum thickness of
26、150 m when tested by microscopic examination per Appendix A. Maximum thickness of the coating shall be controlled by the maximum OD (Table 6). Actual thickness of the coatings in the GN finish shall be monitored circumferentially and longitudinally for each tube line. A sampling plan shall be refere
27、nced in the control plan. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14658 Copyright 2012 General Motors Company All Rights Reserved
28、 February 2012 Page 4 of 17 Finish Finish Code External Finish Description and Material Requirements Zinc-Aluminum Alloy + Extruded Nylon 612 GY Zinc-aluminum alloy as described above followed by a conversion coating, an epoxy resin based primer, and a topcoat of Nylon 612. Appearance: The topcoat s
29、hall be uniform in color and free from discontinuities such as flow lines, pin holes, craters, or abnormal roughness. The topcoat shall be black in color unless otherwise specified on the engineering drawing Film Thickness: The epoxy primer shall be 0.3 m minimum and the Nylon 612 topcoat shall have
30、 a minimum thickness of 150 m when tested by microscopic examination per Appendix A. Maximum thickness of the coating shall be controlled by the maximum OD (Table 6). Actual thickness of the coatings in the GY finish shall be monitored circumferentially and longitudinally for each tube line. A sampl
31、ing plan shall be referenced in the control plan. Aluminum Plate + Extruded Nylon 11 or 12 AN Hot-dip aluminum, coated to a minimum thickness of 100 m anywhere on the tube, followed by a conversion coating, an epoxy resin based primer, and a topcoat of Nylon 11 or 12. Appearance: The topcoat shall b
32、e uniform in color and free from discontinuities such as flow lines, pin holes, craters, or abnormal roughness. The topcoat shall be black in color unless otherwise specified on the engineering drawing. Film Thickness: The epoxy primer shall be 0.3 m minimum and the Nylon 11 or 12 topcoat shall have
33、 a minimum thickness of 120 m when tested by microscopic examination per Appendix A. Maximum thickness of the coating shall be controlled by the maximum OD (Table 6). Actual thickness of the coatings in the AN finish shall be monitored circumferentially and longitudinally for each tube line. A sampl
34、ing plan shall be referenced in the control plan. Aluminum Plate + Extruded Nylon 612 AY Hot-dip aluminum, coated to a minimum thickness of 100 m anywhere on the tube, followed by a conversion coating, an epoxy resin based primer, and a topcoat of Nylon 612. Appearance: The topcoat shall be uniform
35、in color and free from discontinuities such as flow lines, pin holes, craters, or abnormal roughness. The topcoat shall be black in color unless otherwise specified on the engineering drawing. Film Thickness: The epoxy primer shall be 0.3 m minimum and the Nylon 612 topcoat shall have a minimum thic
36、kness of 120 m when tested by microscopic examination per Appendix A. Maximum thickness of the coating shall be controlled by the maximum OD (Table 6). Actual thickness of the coatings in the AY finish shall be monitored circumferentially and longitudinally for each tube line. A sampling plan shall
37、be referenced in the control plan. Zinc Plate + PVF Coating ZP Electroplated zinc, coated to a minimum thickness of 22 m anywhere on the tube, followed an approved pretreatment process and an approved PVF coating. Thickness Measurements: The PVF coating of the ZP finish shall have a minimum thicknes
38、s of 15 m anywhere on the tube as measured by the procedures in Appendix A. Actual thickness of the coatings in the ZP finish shall be monitored circumferentially and longitudinally for each tube line. A sampling plan shall be referenced in the control plan. Zinc Plate + Modified Epoxy Ester Paint Z
39、M Electroplated zinc as described above followed by an approved pretreatment process and approved modified epoxy ester paint. Thickness Measurements: The modified epoxy ester paint of the ZM finish shall have a minimum thickness of 30 m anywhere on the tube as measured by the procedures in Appendix
40、A. Actual thickness of the coatings in the ZM finish shall be monitored circumferentially and longitudinally for each tube line. A sampling plan shall be referenced in the control plan. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reprodu
41、ction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14658 Copyright 2012 General Motors Company All Rights Reserved February 2012 Page 5 of 17 Table 2: GME Material Supplied for Passenger Car Applications d1 Note 1 in mm s Note 1 in mm Weight Note 2 in kg
42、/1000 m 2 kg Burst Pressure in MPa Permissible Operating Pressure in MPa Smallest Bending Radius r Note 3 In mm Tolerances Cylinder Roller Profile Roller Note 4 0.05 mm 0.03 mm Without Internal Punch With Internal Punch 2.5 0.5 25 141 58 5 - - 0.7 31 203 83 3.2 0.5 33 108 44 6 6 - 0.7 43 156 64 4 0.
43、5 42 84 34 8 7 - 0.7 57 122 50 4.75 0.7 70 101 41 13 8 - 5 0.7 73 94 38 15 9 - 6 0.7 89 80 32 25 12 - 6.35 0.7 93 73 30 28 13 - 7 0.7 107 66 27 35 16 13 8 0.7 125 57 23 46 19 14 1.0 174 84 34 9 0.7 144 50 21 59 23 15 9.5 0.7 151 47 19 68 25 16 10 Note 5 0.7 154 45 18 76 27 17 1.0 219 66 27 12 Note 5
44、 0.7 192 37 15 128 41 24 257 54 22 Note 1: Underlined values and wall thickness of 0.7 mm preferred. The specified tolerances are applicable only for Type A tubes: For Type B tubes the upper tolerance limit may be exceeded by 0.04 mm, for Type C by 0.08 mm and for Type E by 0.17 mm. The limiting siz
45、es of the outside diameters may deviate on bending locations by about 10% from the respective actual diameter of the straight portion of the tube caused by non-circularity (ovality) as far as the specified smallest binding radii are not exceeded. Note 2: For zinc coated tubes the weight will be incr
46、eased by 2.5% and for plastic coated tubes 3.0%. Note 3: Bending radius at bending in cold condition without filling. Note 4: With these radii the maximum stress within the wall is obtained. Note 5: A tolerance of 0.07 mm is valid. Table 3: Permissible Deviations for Passenger Vehicles Length in mm
47、Tolerances 500 2 500 2000 3 2000 5000 5 5000 10 Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14658 Copyright 2012 General Motors Compa
48、ny All Rights Reserved February 2012 Page 6 of 17 Table 4: GME Material Supplied for Commercial Vehicle Applications Diameter in mm Wall Thickness in mm Burst Pressure in MPa Smallest Bending Radius Note 1 in mm Tolerances Tolerances Hand Bend Mechanical Bend Note 2 3.2 0.7 172 9.5 6.5 - 4.0 0.7 124
49、 19 9.5 - 4.76 0.7 114 19 9.5 - 6.35 0.7 86 28.5 12.7 9.5 7.39 0.7 72 35 19 12.7 9.53 0.7 57 68 22 16 12.7 0.7 42 114 45 - Note 1: Bending radius at bending in cold condition without filling. Note 2: With these radii the maximum stress within the wall is obtained. Table 5: Permissible Deviations for Commercial Vehicles Length in mm Toleranc
