API STD 677:2006 pdf download

API STD 677:2006 pdf download.General-Purpose Gear Units for Petroleum, Chemical and Gas lndustry Services.
2.5.1.4 All internal piping should preferably he welded and should prefrahly use flanges for all connections. Any threaded piping shall be a minimum of Schedule 80 and shall be seal welded at flanges (see 2.6.2.1 .d).
2.5.1.5 When tubing is used internally, it shall be stainless steel tubing in accordance with 3.5.1 and 2.5.1.6.
2.5.1.6 The design of internal piping and oil pans shall achieve proper support and protection to prevent damage from vibration or from shipment, operation, and maintenance. Cantilevered piping shall include reinforcing gussets in two planes at all pipe-to- flange connections.
2.5.1.7 Casings shall be designed to permit rapid drainage of lube-oil and to minimize oil foaming that could lead to excessive heat rise of the oil.
2.5.1.8 A replaceable filter-breather with a filtration rating of 10 micron particles (1()  10) or better shall be provided. The filter-breather shall be designed and located to prevent entrainment or discharge of oil to the atmosphere, pressure buildup in the casing, entrance of water during violent rainstorms, and entrance of dirt entrained in the air. The filter-breather connection shall be at least 3/4 NPT’.
Note: Small gearhoxes may not accommodate this size filter-breather. Alternate configurations shall be as mutually agreed between the purchaser and vendor. Refer to API Std 614, Appendix E. for definition of filtration rating.
• 2.5.1.9 If specified, a non-replaceable, cleanable filter-breather shall be provided constructed of stainless steel with stainless steel or copper-nickel alloy internals, and shall be designed and located to prevent entrainment or discharge of oil to the atmosphere, pressure buildup in the casing, entrance of water during violent rainstorms, and entrance of dirt entrained in the air. The filter-breather connection shall be at least 3/4 NPT, and its construction shall permit easy disassembly for inspection and cleaning.
Note: The conventional filter breather as described in this paragraph may permit contaminated air to be drawn into the gear case and contaminate the oil.
• 2.5.1.10 If specified by the purchaser and accepted by the vendor, gear unit casings shall be provided with purge oil mist to prevent casing contamination from environmental factors.
Note: This requires the oil mist lubricant to he the same as the main lubricant for the gear unit to prevent oil quality degradation. Careful considëration should be given to how the gear unit reservoir oil level, whether the reservoir is integral in the sump or on an external console, would be maintained where oil mist condensation is a possibility.
2.5.1.11 A removable, gasketed inspection cover or covers shall be provided in the gear casing to permit direct visual inspection of the full-face width of the gear elements. The inspection opening or openings shall preferably be at least one-half the width of the gear face.
2.5.1.12 Permanent coatings or paint shall not be applied to the interior of the casing unless the purchaser approves in advance the material and method of application.
2.5.1.13 On units that have pressurized oil systems with pitch line velocities above 15 mIs (3,000 ft/mm). the gearbox casing shall be designed so that the gears do not dip into the oil during operation or upon shutdown. Gear units at or below 15 mIs (3,000 ft/mm) pitch line velocity may dip into the oil; however, above 10 rn/sec (2.000 ft/mm) pitch line velocity, an oil pan shall be used to ensure rapid drainage and to minimize foaming.
2.5.2 Joints
Casing splitlines shall use a metal-to-metal joint (with a suitable joint compound) that is tightly maintained by suitable bolting. Gaskets (including string-type) shall not be used on splitlines for parallel shaft gears.
Note: Due to the interaction of the rotating elements of spiral bevel gear units, it is normally required that the element’s mounting distances be adjustable to achieve proper tooth mesh contact and backlash. When the adjustment is made by shifting axially, in line with the element’s shaft center line of rotation by use of a combination housing cover-hearing carrier, shim type gaskets are permitted.
2.5.3 Bolting
2.5.3.1 Case bolting may be of the through-bolt, studded, or cap-screw type. Threaded bolt holes shall not penetrate through the wall into the interior of the casing. Disassembly shall not require removal of studs.