ISO 12212:2012 pdf download – Petroleum, petro chemical and natural gas industries- Hairpin-type heat exchangers. Provision shall be included to protect tubesheet sealing surface from damage during bundle
inseition or removal.
7.7.5 joint
The tube-to-tubesheet ioint shall be in accordance with the TEMA standard unless otherwise specified by the
7.8 Nozzles and other connections
7.51 Flanges shall be in accordance with the pressure design code unless otherwise specified by purchaser.
7.8.2 ConnectIons DN 40 (NPS 1112) and larger shall be flanged unless otherwise specified by the purchaser.
7.8.3 Connection sizes of DN 32 (NPS 1.114), DN 65 (NPS 2-112), ON 90 (NPS 3-112) or DN 125 (NPS 5) shall not be used.
7.8.4 It welded connections are specified, they shall be bevelled.
7.8.5 Non.flanged connections smaller than ON 40 (NPS 1112) shall be forged couplings with an appropnate rating, for example eqwvalent to ASME B16.1 I class 6000, or shall be integrally reinforced welding fittings with appropriate tapered threads, for example equivalent to ASME Bi 20.1. and shall comply with the pressure design code. Threaded connections shall not be used i hydrogen, sour or wet hydrogen sulfide service. This Indudes auxiliary connections such as vents, drains, instrument connections and chemical dean4ng connections.
7.8.6 Flanged connections shall be of one of the following types:
a) forged Integrally flanged;
b) pipe or forged cylinder welded to forged welding-nedc flange;
C) pipe welded to a forged sup-on flange, except as noted in 7.8.7.
7.8.7 Slip-on flanges shall not be used in any of the following conditions:
a) for design pressure exceeding 2 100 kPa (ga) (300 psig);
b) for design temperature exceeding 400 C (750 F):
C) for corrosion allowance exceeding 3 mm (118 in);
d) ii hydrogen service, sour, or wet hydrogen sulfide service:
0) Ni cyclic service.
• 7.8.8 When specified by the purchaser, the projection of flanged connections shall allow the removal of through-bolting from either sioe of the flange without removing the insulation. This requirement does not apply to the interconnecting nozzles of slacked undts. The Insulation thickness shall be specified by the purchaser.
7.8.9 Integrally reinforced nozzles shaM be designed so that standard spanners (wrenches) fit the nuts without interference from nozzle neck reinforcement
7.8.10 All boll holes for flanged or studded connections shall straddle cenirelines.
7.9.2 When the fixed shell support of a removable-bundle heat exchanger is fixed to the shell, it shall be designed to withstand a longitudinal force equal to 150 % & the bundle mass applied at the heat exchanger bundle centreline. The shear stress for supports shall not exceed 40 % of the yield strength of the material.
7.9.3 Support material in direct contact with the shell shall be of the same nominal composilion as the shell.
7.9.4 The lower shells of stacked removable-bundle heat exchangers shall be designed to carry the superimposed loads without suffering distortion that can cause binding of the tube bundles.
7.9.5 All units shall have at least one earthing lug, welded directly to a suitable shell side component.
7.10 Gaskets
7.10.1 Spiral-wound gaskets, where used, shall be provided with a means to prevent over-compressrnn and buckling.
7.10.2 Gaskets shall be of a one-piece design, Gaskets made integral by no more than two welds are acceptable.
7.11 Flanged external girth joints
7.11.1 External girth joints shall be of through-bolted construction, unless otherwise approved by the purchaser.
7.11.2 Minimum bolt diameter shall be 12mm (112 in).
7.11.3 Slip-on flanges shall not be used as girth flanges.
7.11.4 The gap between mating flanges after assembly shall be not less than 3 mm (1)8 in) and this gap shall extend within the bolt Orcle to allow checking the flanges for radial distortion caused by an excessive bolt Iced.
7.11.5 Through-hardened washers shall be provided under nuts for all bolts having a diameter of 38 mm (11,2 in) or larger unless hydraulic boll tensioners are used. The washers shall be at least 6 imi’i (1/4 in) thick.
7.11.6 The purchaser shall specify if bolt-tightening devices will be used When used, the nozzles and/or girth flanges shall be designed to alow adequate clearance.
7,12 Cladding for corrosion allowance
7.12.1 If cladding (including weld overlay) is used. tne cladding thickness shall e used only as corrosion allowance and not for pressure design.
7.12.2 The cladding thickness at the tube side face of a tubesheet shall be not less than 10 mm (3/8 in) when tubes are expanded only, and 5 mm (3)16 in) when tubes are welded to the tubesheet. If grooves are use, the first groove shall be within the tube side cladding.
7.12.3 The cladding thickness on the shell side face of a tubesheet shall be not less than 10mm (3/8 in).