Nozzle loads – Part 2

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1.1         Proprietary Equipment

Various Mechanical equipments like Pumps, Compressors, Expanders, Plate-fin heat exchanger, Air cooled Heat Exchanger etc. are classified under this category. Allowable loads for the nozzles of these equipments are generally available from equipment supplier. However, some of the proprietary equipment are designed and constructed as per International codes with standard set of allowable loads. In any case, loads imposed by the connected piping system shall be confirmed and approved the supplier.

API 610, Table 5 gives the allowable forces and moments on the Pump Nozzles (Suction and Discharge). However, if the loads acting on the Pump nozzles exceed these values, the allowable loads can be increased to 2 times, provided the criteria specified in Annex F are satisfied. This shall be approved and confirmed by the Pump Vendor. As a general practice, approval shall be taken from the vendor for 2 times API 610 at the initial stage of the project.

However,if one or more components of the forces and moments are still exceeding, same shall be approved & agreed with the Pump Vendor.

  • Metering Pumps/Pumps as per NFPA code

The minimum allowable nozzle loads shall be as provided by the Pump Supplier.

  • Pumps (API 676, Rotary Positive Displacement)

The minimum allowable nozzle loads shall be as per API676, Table 2. However, if one or more components of the forces and moments are still exceeding, same shall be approved & agreed with the Pump Vendor.

  • Centrifugal Compressors & Turbo Expanders

The allowable forces and moments acting on the nozzles of centrifugal compressors shall be designed in accordance with API 617, the forces and moments shall be 1.85 times the values based on the load criteria of NEMA SM23. However, if one or more components of the forces and moments are still exceeding, same shall be approved & agreed with the Vendor.

The minimum allowable nozzle loads shall be as per API 618 values. However, if one or more components of the forces and moments are still exceeding, same shall be approved & agreed with the Vendor.

  • Rotary Positive Displacement Compressors (API619)

The minimum allowable nozzle loads for Rotary Positive Displacement Compressors is generally taken as 1.85 times NEMA SM23 Values. However, if one or more components of the forces and moments are still exceeding, same shall be approved & agreed with the Vendor.

  • Brazed Aluminium Plate-Fin Heat Exchangers

The allowable nozzle loads for Brazed Aluminium Plate-Fin HeatExchanger shall be 3 times the value in ALPEMA (Standards of theBrazed Aluminium Plate-Fin Heat Exchanger Manufacturer’s Association) Table 5-1. However, it shall be approved and agreed by the Vendor.

  • Air Cooled Heat Exchangers

The minimum allowable nozzle loads on Air-Cooled Heat Exchangers due topiping reactions shall be as listed below.

Nozzle Rating

Allowable Load

150 & 300 #

2 times API 661 Values

600#

4 times API 661 Values

900#

6 times API 661 Values

However, it shall be approved and agreed by the Vendor.

  • Gas Turbines

The minimum allowable nozzle loads for Gas Turbines shall be as provided by Supplier.

  • Fired Heaters

The minimum allowable nozzle loads for Fired Heaters shall be THREE times as specified in API-560. In case the same is procured as a package item, Nozzle loads shall be as per Cl. 5.2.14 below.

  • Steam Turbines-NEMA SM 23

The minimum allowable nozzle loads for Steam Turbine is generally taken as 1.85 times NEMA SM23 Values. However, if one or more components of the forces and moments are still exceeding, same shall be approved & agreed with the Vendor.

  • Reforming furnace-Vendor to give
  • Large storage tanks-API 650
  • Any other proprietary equipment

The minimum allowable nozzle loads for any other proprietary equipment shall be as provided by Supplier.