February 1997
KRUPP UHDE STANDARD
Vessels and equipment AIR-COOLED HEAT EXCHANGERS
UN 2100-01
General specification
Part 2
Behälter und Apparate; Luftgekühlte Wärmeaustauscher; Technische Lieferbedingungen
Supersedes 87-04
Contents 1
General .................................................................................................................................................................1
2
Design...................................................................................................................................................................1
3
Fabrication............................................................................................................................................................2
4
Tests and inspections .........................................................................................................................................3
5
Marking .................................................................................................................................................................3
1
General
1.1
Scope of application
The present general specification applies to the design, fabrication and inspection of air-cooled heat exchangers. It should be read in conjunction with the associated technical specifications and the applicable codes and standards.
1.2
Contradictions and deviations
If the requirements outlined in the present general specification are in contradiction with the contents of the technical specification, the latter takes precedence. If the manufacturer wants or has to deviate from the codes and standards specified in the technical specification, he shall obtain the written approval of the purchaser prior to the commencement of work.
2
Design
All components shall correspond to the latest state of technology. Deviations from generally proven designs and special designs require the written approval of the purchaser.
2.1
Types, installation
Unless otherwise specified, forced-draught heat exchangers with blower fans shall be provided. Natural-draught air-cooled heat exchangers and heat exchangers with exhauster fans require written approval of the purchaser. The arrangement of the cooling elements (horizontal, vertical, roof-type, V type or special type) is indicated in the technical specification. Deviations are permitted if the physical properties of the fluid to be cooled and the arrangement conditions are taken into consideration, but require the written approval of the purchaser. To ensure an unimpeded cooling air supply, all buildings and plant sections located in the vicinity of the aircooled heat exchanger shall be taken into account when determining the height of supports. Hot air recirculation shall be avoided.
2.2
Cooling elements
The cooling elements (tube bundles) shall be of the torsion-proof and self-supporting type. The dimensions and weight of a cooling element shall facilitate transport and assembly. Facilities for absorbing the heat expansion of the tubes are required. Vibration of the tubes shall be prevented by suitable means. The tubes shall be welded into the tube sheets. Rolling the tubes into the tube sheets is only permitted if approved by the purchaser in writing.
2.3
Tubes (finned tubes)
The tube type to be used is indicated in the technical specification. If selection of the tube type is permitted, Continued on pages 2 to 3 Date
Prepared
Date
© 1997 Krupp Uhde GmbH
Checked
Date
Approved
Technical discipline: EN-EP
Page 2 UN 2100-01 Part 2 same shall take into consideration the arrangement and operating conditions. The following temperature limits (max. fluid temperature) shall be observed: a) L-FIN type ≤ 120°C (spiral tube with L foot fin) b) G-FIN type ≤ 400°C (spiral tube with grooved fin) c) Extruded FIN type ≤ 200°C (bimetal tube with drawn-out fin) d) Hot dip galvanized FIN type ≤ 250°C (round, elliptical or oval) The selection of the material shall take into consideration any corrosive effects of the cooling air. Finned tubes of carbon steel shall be of the seamless type with a minimum wall thickness of 2 mm. Tubes of stainless steel, titanium or other non-ferrous metals may be welded in the longitudinal direction. The fin pitch shall not be less than 2 mm. The fins shall terminate at least 40 mm from the tube ends. 2.3.1 Element headers The design of the headers shall take into consideration the pressure, temperature of and the fouling caused by the fluid: • Fully welded semi-circular headers • Headers with a bolted removable cover plate. The nozzles shall be arranged in such a manner that the cover can be removed without the necessity of dismantling any tubes (inspection and cleaning). • Plug-type headers • Split or divided headers. This design shall be used if an excessive load on the tubes or tube sheets is to be expected due to appreciable differences in temperature between the passes. • Special designs such as circular headers for fluids under high pressure. This application requires the written approval of the purchaser. All headers must be provided with vent and drain connections.
2.4
Fans
Low-noise and non-vibrating axial fans shall be used. Where noise suppression is of particular importance, fans with 5 to 8 blades of special profiles and low peripheral speed shall be used. Preference shall be given to fan blades of glass-fibre-reinforced plastics. The fan blades shall be thoroughly balanced (statically and also dynamically as far as this is possible). They shall be appropriately marked for installation. The blade angles shall be adjustable during shut-down. The use of fans which are adjustable in operation (pneumatically) may be required for reasons of control.
2.5
Drives
The fans are driven by electric motors. Transmission may be direct or via V-belt drives. The use of gears requires the purchaser's approval. The rated output of the motors shall include allowances for extreme ambient temperatures as well as for possible blade adjustment (rated output: ≥ 1.2 times the required shaft power).
2.6
Louvers
If louvers are required, same shall be arranged above the cooling elements or, in special cases, on the intake side underneath the fans. The louvers shall be actuated manually or by means of actuators.
2.7
Drawings
The drawings must contain all essential components of the air-cooled heat exchanger and of the accessories including all dimensions, position of the connections, as well as load data for the foundations, itemizing of the individual parts with parts list, weights, and nozzle table.
2.8
Materials
The materials used shall correspond to the technical specification. Only perfect materials and new gaskets must be used. Deviating, but equivalent, materials require the written approval of the purchaser prior to use.
3
Fabrication
Fabrication shall be effected competently and properly while observing the applicable specifications, codes and standards.
UN 2100-01 Part 2 Page 3
4
Tests and inspections
During inspection by the purchaser and/or his representative, each heat exchanger including accessories shall be subjected to the following checks and tests: • Scope of supplies (including anchor bolts, special tools, spare parts) • Dimensional accuracy and workmanship (visual check) • Conformity of the materials with the specifications, parts lists, codes and standards • Material certificates • Leakage test of the tube-to-tube-sheet joints • Pressure test As regards the permissible chloride content of the water used for the pressure test, Uhde standard UN V416-04 Part 1 applies to components of austenitic steel coming in contact with the process fluid.
5
Marking
All cooling elements (tube bundles) shall be fitted with a name plate according to Uhde standard UN 2000-09 Part 1. The plate shall be mounted at a conspicuous place on the inlet header.
Reference standards Uhde standards: UN 2000-09 Part 1 Name plate for vessels and equipment UN V416-04 Part 1 Quality requirements for water used for pressure tests and flushing Other codes and standards API 661 Air-cooled heat exchangers for refinery service
