When specified, tapped holes shall be provided in the coupling for trim balancing. The number, size, depth, and location of such holes shall be agreed upon by the purchaser and the vendor. The optimum location for keyed hubs is generally on the outboard faces of the hubs, midway between the inside and outside diameters of the hub barrel. The optimum location for keyless (hydraulically fitted) hubs is generally on the coupling flanges, between the bolt holes of the flange.
Note: Because of eccentricity of the shaft end or incompletely filled keyways trim balancing the rotor after the coupling hub has been mounted may be advisable. The practice normally precludes moving the hub to another rotor, unless balance is achieved by using balance holes. When balance holes are used the hub can always be returned to its original state of balance by removing the weights inserted into the holes.
Materials
1. Except as required by the data sheets or this standard, materials of construction shall be the vendor’s standard for the specified operating conditions.
2. Material shall be identified in the proposal with their applicable ASTM, AISI, ASME or SAE numbers, including the material grade. When no such designation is available the vendor’s material specification, giving physical properties, chemical composition, and test requirements shall be included in the proposal.
3. Neither copper nor copper alloys (excluding Monel and precipitation-hardened stainless steels) shall be used for coupling parts.
4. All metallic components of the coupling shall be made from high-quality material manufactured by hot rolling, cold finishing, or foreign and shall be appropriately heat treated. Hubs and sleeves shall be made of alloy steel. Flexing elements in flexible-element couplings shall be of corrosion-resistant material or shall be suitable coated. The vendor shall state the nature of the coating and how it must be applied. The purchaser will specify whether all other parts shall be made from corrosion resistant material or suitably coated.
5. The purchaser will specify any corrosive agents present in the environment, including constituents that may cause stress corrosion cracking.
6. All fasteners shall be of heat-treated alloy steel, SAE J 429, Grade 5, or better. The threads shall be American Standard unified fine thread series. Materials shall be corrosion resistant to the specified environment. If plated bolts are required, they shall be treated properly to avoid cracking caused by hydrogen embrittlement. The quality of the nuts shall be at least equal to that of the bolts.
Note: Because of eccentricity of the shaft end or incompletely filled keyways trim balancing the rotor after the coupling hub has been mounted may be advisable. The practice normally precludes moving the hub to another rotor, unless balance is achieved by using balance holes. When balance holes are used the hub can always be returned to its original state of balance by removing the weights inserted into the holes.
Materials
1. Except as required by the data sheets or this standard, materials of construction shall be the vendor’s standard for the specified operating conditions.
2. Material shall be identified in the proposal with their applicable ASTM, AISI, ASME or SAE numbers, including the material grade. When no such designation is available the vendor’s material specification, giving physical properties, chemical composition, and test requirements shall be included in the proposal.
3. Neither copper nor copper alloys (excluding Monel and precipitation-hardened stainless steels) shall be used for coupling parts.
4. All metallic components of the coupling shall be made from high-quality material manufactured by hot rolling, cold finishing, or foreign and shall be appropriately heat treated. Hubs and sleeves shall be made of alloy steel. Flexing elements in flexible-element couplings shall be of corrosion-resistant material or shall be suitable coated. The vendor shall state the nature of the coating and how it must be applied. The purchaser will specify whether all other parts shall be made from corrosion resistant material or suitably coated.
5. The purchaser will specify any corrosive agents present in the environment, including constituents that may cause stress corrosion cracking.
6. All fasteners shall be of heat-treated alloy steel, SAE J 429, Grade 5, or better. The threads shall be American Standard unified fine thread series. Materials shall be corrosion resistant to the specified environment. If plated bolts are required, they shall be treated properly to avoid cracking caused by hydrogen embrittlement. The quality of the nuts shall be at least equal to that of the bolts.
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