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API STD 677:2006 pdf download

API STD 677:2006 pdf download.General-Purpose Gear Units for Petroleum, Chemical and Gas Industry Services. All of the purchasers connections shall he accessible 11w disassembly without requiring the machine. or any major pan of the machine, to be moved. The concentricity of the bolt circle and the bore of all casing flanges shall be such that the area of the machined gasket. seating surface is adequate to accommodate a complete standard gasket without protrusion of the gasket into the fluid flow.
2.7.1 General Gear-teeth profiles shall be manufactured by the generating. shaping. or form process. Gears and pinions with pitch line elocities below 15 m/s (3,000 ftlmin may be finished unassembled with their shafts, Helical gears and pinions with pitch line velocities at or above 15 rn/s shall be finish cut or ground assembled with their respective shafts. Shaving and shaping cutters shall have a hunting tooth combination with the work piece. For pitch line velocities up to 15 ni/s (3,0(K) ft/mm), gear teeth shall be of ISO 1328 Grade 8 accuracy or better. For pitch line velocities between 15 and 30 rn/s (3.000 and 6.0(X) ft/mm), gear teeth shall be of ISO 1328 Grade 7 accuracy or better. For pitchline velocities between 30 and 45 rn/s 6.(XX) and 9.000 ft/mm). gear teeth shall be of ISO 1328 Grade 6 accuracy or better. For pitchline velocities above 45 rn/s (9,0(X) ft/mm). gear teeth shall he of ISO 1328 Grade 5 accuracy or better. The tooth surface on loaded faces of completed gears shall have a finish. as measured along the pitch line, of 0.8 pm (32 jim.) Ra above a 20 ni/s (4.0(X) ft/mm) pitch line velocity limit and 1.6 pm (64 pin.) Ra at or below a 20 ni/s (4.000 fl/mm) minimum pitch line velocity limit. Sec also ISO TR 10064-1 on measuring methods, The design of single-helical and right-angle gears shall be such that the effects of the moments on the gear elements. resulting from axial tooth reaction at the gear mesh, will not impair the expected performance of the gear unit. Hunting tooth combinations are required. To achieve this, it may be necessary for the purchaser to adjust the exact gear ratio. If this is impractical, the purchaser and the vendor shall negotiate a solution. Each helical gear and pinion of parallel shall gear sets shall he supported between two bearings. Overhung designs are acceptable only below IS rn/s (3.000 ft/mimi) pitch line velocity and 225 kilowatts (300 horsepower). There are two types of mountings for spiral bevel gear units, straddle and overhung. The mourning configuration is dictated by the size and ratio of the unit. When the gear diameter is large enough, one of the bearings shall be mounted inboard of the pitch cone (small end) iw straddled. If the gear diameter will not permit straddle mounting, the element may he overhung. The vendor shall indicate on the data sheets the pinion mounting conhguration. straddle or overhung.
2.7.2 Quality Assurance Each pair of mating gears for parallel shall units shall have a contact check in the gear casing at the vendor’s shop. Those gear sets operating above 20 mis (4,000 ft/mm) pitch line velocity shall be checked for contact on a contact checking stand and in the job casing at the vendor’s shop.
A thin coating of color transfer material (such as Prussian bluet shall be applied at three locations 120 degrees apart to four or more teeth of the dry degrcascd gear. With the gear elements held firmly on the correct center distance and with the shaft centerlines parallel within 42 pm per m (0.5 mils’ft) with a total misalignment of not more than 25 pm (I mil). the coated teeth shall be rotated through the mesh with a moderate drag torque applied in a direction that will cause the teeth to contact on the normally loaded laces. The color transfer shall show evidence of contact distributed across the face as prescribed by the vendor. Prior to the contact tests, the vendor shall make available to the purchaser a contact drawing or vendor engineering specification that defines the expected and acceptable contact. Unmodified tooth profile leads shall show a minimum contact of 70% along the axis and 30% radially. Contact drawings or specifications and the results of the contact checks shall be delivered with the unit documentation. The results of the contact check shall be preserved by lifting the colors from a tooth, by applying and peeling ofT a strip of clear adhesive tape arid then sticking the tape to an annotated sheet of paper. Spiral bevel gear-tooth contact shall be checked per Appendix G.


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