API 613:2003 pdf download

API 613:2003 pdf download.Special Purpose Gear Units for Petroleum, Chemical and Gas Industry Services.
Notes:
1. Refer to AGMA 925 for additional infomiation.
2. When high speed gears are subject to highly loaded conditions and high sliding velocities the lubricant film may not adequately separate the surfaces. This localized damage to the tooth surface is referred to as “scuffing” (sometimes incorrectly called scoring). Scuffing will exhibit itself as a dull matte or rough finish usually at the extreme end regions of the contact path or near the points of a single pair of teeth contact resulting in severe adhesive wear.
Scuffing is not a fatigue phenomenon and may occur instantaneously. The risk of scuffing damage varies with the material of the gear, the lubricant being used, the viscosity of the lubricant, the surface roughness of the tooth flanks, the sliding velocity of the mating gear set under load and the geometry of the gear teeth.
Changes in any or all of these factors can reduce scuffing risk.
2.2.7 Deviations
It is recognized that special cases will exist in which it may be desirable to deviate from the rating niles specified in 2.2. 1 through 2.2.5 The vendor shall describe and justify such deviations in the proposal.
2.3 CASINGS
2.3.1 Design Parameters
2.3.1.1 Gear casings shall he either cast or tabricated and shall he designed and constructed to maintain rotor alignment under all load conditions.
2.3.1 .2 Provision shall he made to permit doweling or keying the casing to the soleplate or baseplate at two points as close as possible to the vertical plane of the pinion’s centerline (to minimize misalignment of the high-speed pinion with connected equipment). Casings not doweled or keyed by the vendor shall be provided with dowel starter holes. Drilling interferences in the held installations should be considered in determining the location and angle of the starter holes,
2.3.1.3 Mounting surfaces shall meet the following criteria:
a. They shall be machined to a finish of 6 im (0.00025 in.) arithmetic average roughness (Ra) or better.
b. To prevent a soft foot, they shall be in the same horizontal plane within 25 jim (0.001 in.).
c. Each mounting surface shall be machined within a flatness of 42 jim per linear meter (0.0005 in. per linear ft) of mounting surface.
d. Different mounting planes shall be parallel to each other within 50 jim (0.002 in.).
e. The upper machined or spot faced surface shall be parallel to the mounting surface.
Hold-down bolts holes shall he drilled perpendicular to the mounting surface or surfaces, machined or spot faced to a diameter three times that of the hole and to allow for equipment alignment, he 15 mm (1/2 in.) larger in diameter than the hold-down bolt.
2.3.1 .4 The equipment feet shall be provided with vertical jackscrews.
2.3.1.5 Bores shall be machined to a sufficient degree of accuracy so that a gear set that contacts correctly on true centers on a rotor checking stand will also contact correctly in its own casing.
2.3.1.6 Casings shall be designed to prevent damage due to distortion caused by temperature, torque, and allowable external forces and moments.
2.3.1 .7 To the maximum extent practicable. casings shall he designed with internal oil passages to minimize external piping. All internal piping should preferably be welded and should preferably use flanges for all connections. Any threaded piping shall be a minimum of Schedule 80 and shall he seal welded at flanges (see 2.4.6.4).
2.3.1 .8 Where internal space does not permit the use of DN15. DN2O, oi DN25 (1/2 3/4, or 1-in.) ASTM A 312 pipe, seamless steel tubing conforming to ASTM A 192 with stainless steel fittings, or stainless steel tubing conforming to ASTM A 269 with stainless steel fittings may be furnished. Tubing thicknesses shall meet the requirements of Table 6. The make arid model of fittings shall be subject to the purchaser’s approval.
2.3.1.9 The design of internal piping shall achieve proper support and protection to prevent damage from vibration or from shipment. operation, and maintenance. Canlilevered piping shall include reinforcing gussets in two planes at all pipe-to-flange connections.
2.3.1.10 Internal piping and oil passages shall be cleaned to remove all foreign material.
2.3.1.11 Casings shall be designed to permit rapid drainage of lube oil and to minimize oil foaming, which could lead to excessive heat rise of the oil. For gears with pitch line velocities of more than 1 25 m/sec (25,00() ft/mm.), consideration shall be given to special designs such as the following.