5.2　General Requirements

5.2.1　Purchaser shall provide normal operating case,guarantee case,and all other cases that Vendor could meet with,including startup and shutdown conditions.

5.2.2　The method of connection between coupling and shaft should be one of the following:

—Integrally flanged shaft ends

—Hydraulically fitted tapered shaft ends

—Cylindrical shaft ends with keys

5.2.3　For metallic flexible-element couplings,the purchaser shall inform the vendor with the difference between normal operating condition and other condition(such as cold static condition),and decide whether to apply pre-compression and pre-stretch or not.

5.2.4　Purchaser and vendor shall negotiate if it is proposed to fit a torque-limiting device.

5.2.5　A limited-end-float coupling is required if the coupled machines does not have a thrust bearing.

5.2.6　The purchaser shall define the connection details of shaft ends.

5.2.7　If specified by purchaser,an idling adapter shall be provided to enable driving machine to operate above its first lateral critical speed.

5.2.8　Vendor shall determine and advise the purchaser whether electric insulation is necessary,this shall be the case with large electric motors fitted with hydrodynamic bearings and steam turbines handling wet steam.

5.2.9　If specified by purchaser,or trains driven by gas turbines,a coupling with torque meter shall be provided.

5.2.10　Precision balancing test of coupling shall be completed individually,and ISO 1940-1 Grade 2.5 shall be achieved at least,coupling shall be assembly balanced.

5.2.11　An assembly balance check shall be required for a coupling connected to a machine which may be required to run continuously within 20% of any lateral critical speed.

5.2.12　A balance repeatability check should be required when couplings need to be disassembled.

5.2.13　When the guard is supplied by vendor,the design details of guard shall be reviewed and approved by purchaser.

5.2.14　The spacer length shall be sufficient to enable the following maintenance operation to be carried out without moving either of the coupled machines:

—Removal and replacement of the coupling in its entirety;

—Maintenance of bearings,seals and impellers assembly of a"back-pull-out"type machine;