The Structural Engineer's Corner

Eng. Onorio Francesco Salvatore

Dead loads according to the Process Industry Practices (PIP)

Written By: Lexatus - Sep• 28•14

Dead loads - Onorio Francesco Salvatore

In this post we are going to discuss about the loads defined in the Process Industry Practices (PIP). The PIP is a self-funded consortium of process industry companies that publishes common industry practices for projects and maintenance work. PIP develops “Practices” that are a compilation of Engineering standards from different Engineering disciplines.

According to PIP, but the definition is common in every standard, dead loads are the actual weight of materials forming the building, structure, foundation and all permanently attached appurtenances.

Fixed process equipment machinery, piping, valves, electrical cable tray, including their contents, are considered as dead loads.

In PIP STC01015 – Structural Design Criteria, PIP adopts a specific nomenclature for the various types of loads: Ds, Df, De, Do and Dt.

They are defined as:

– Ds = Structure dead load, that is the weight of the materials forming the structure, excluding process equipment, vessels, tanks, piping and cable trays. Are included in this category also the foundation, soil above the foundation resisting uplift and, in general, all permanently attached appurtenance such as lightning, instrumentation, HVAC, sprinkler and other similar systems.

– Df = Erection dead load, that is the fabricated weight of process equipment or vessels. It is normally taken from the certified equipment or vessel drawing.

– De = Empty dead load of the empty process equipment. The difference with the erection dead load is that in this case all the attachments, trays, internals, insulation, fireproofing, agitators, piping, ladders, platforms, etc. are included.

– Do = Operating dead load. It is defined as the empty weight of the process equipment, vessels, tanks, piping and cable trays plus the maximum weight of the contents (fluid load) during normal operation.

– Dt = Test dead load. It is defined as the empty weight of process equipment, vessels, tanks and/or piping plus the weight of the test medium contained in the system. The test medium is usually specified in the contract documents or by the owner. Unless otherwise specified, PIP suggests to use a minimum specific gravity of 1.0 as test medium (water). Equipment and pipes that may be simultaneously tested shall be included. Cleaning load shall be used for test dead load if the cleaning fluid is heavier than the test medium.

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Eng. Onorio Francesco Salvatore

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