API Spec 12K:2008 pdf download
API Spec 12K:2008 pdf download.Specification for Indirect Type Oilfield Heaters.
5.1.2 Design Temperature
The maximum design temperature rating shall be 25OF.
5.1.3 Working Pressure of Flanges. Valves, and Fittings
Pressure rating for flanges attached to coils shall be determined in accordance wiifl ANSlASlvtE 1 bt or Afri bA. Pressure ratings for clamp type connectors attached to coils and valves. chokes or fittings with flanged ci’ clamp type connections shall be determined in accordance with API 6A, The nominal bore of the butt-weld flanges and fittings shall be the same as the nommal inside diameter of the pipe to which they are welded, provided the bore does not exceed the maximum permitted by the applicable specification.
Pressure ratings for proprietary valves, fittings, unions and chokes attached to or supplied with coils shall be the rating supplied by the manufacturer of the component. Where the component is classified only by test pressure, the maximum working pressure shall not exceed 67% of the test pressure.
Pressure ratings for forged steel socket-welded and threaded couplings and fittings attached to or supplied with coils shall not exceed the apphcable pressure class of the fitting as described in ANSIIASME 81611.
5.1.4 Internal WorkIng Pressur.
The maximum internal working pressure for various commonly used nominal pipe sizes is tabulated in Table 2. Where a coil assembly contains components such as unions, chokes, flanges, etc.. having a lower working pressure, the coil shall be rated at the lowest working pressure of any component.
5.1.5 Higher Coil Working Pressure
Heather coils for pressures greater than those detemi.ned m accordance with Equation (2) shall not be furnished under this specification.
5.1.6 Coil Removal
The coil section shall be removable from the shell opposite from the flrebox end to facilitate inspection and repair. The coil section shall be adequately supported for normal operation and shipment.
5.2 Shell Design
The minimum requirements for indirect heater shells shall be in accordance with the following (see Annex E)
5.2.1 Shell Working Pressure
The shell shall be designed to operate at or near atmospheric pressure. In no case shall the operating pressure exceed 1 psig.
5.2.2 Shell Form
The shell may be either cylindrical with flat end dosures that may either be welded or baited to the shell, or rectangular with a structural framework to which flat plates are welded on the top, bottom, and sides.
5.2.3 Minimum Thickness
The mlnwnum thidness of cylW&lcal and rectangular shells shall be ii In. In the case of plate or 7.gage (0.1793-In. nominal) in the case of sheet. These minimum thicknesses also apply to end dosures for cylindrical shels, The minimum thickness shall be increased as necessary to meet design requirements.
5.2.4 Allowable Stresses
The allowable stresses used in all structural calculations shall be in accordance with the Amencan Institute of Steel Construction Manual. Allowable shear stress is 40% of the specified minimum yield, allowable tensile and conressien stresses are 60% of the specified minimum yield, and allowable bending stresses are 66% of the specified minimum yield strength. Specified minimum yield strength is to be taken from the apprepriate material specification.
5.2.5 Support Design
Cylindrical shells are nomialy supported on two saddles or with angle legs. Rectangular shells are normally supported on a structural steel skid. Consideration shall be given to supports to ascertain structural integrity. The manufacturer shall consider loads imposed by testing, lifting, transportation, wind, earthquake, and normal operation.
5.2.6 Suggested Guidelines
Some suggested structural design procedures and guidelmes are given In Annex E.
5.3 Standard Firebox Rating
Firebox ratings for heaters conforming to this specification shall be as listed in Table 4 and specified on the purchase order, unless otherwise agreed on between the purchaser and manufacturer. The firebox shall be removable from the shell opposite from the coil end to facilitate Inspection and repaIr. The firebox shall be adequately supported for normal operation and shipment.
