Maximum allowable working

Find the maximum allowable working stress if this is to equal... 

The hydrostatic testing is the first test used on the lube system. The system is tested while assembled or partially assembled, based on the particular system. A test pressure of VA times the maximum allowable working pressure, a minimum of 20 psi for the oil side, is used for the test. For the oil-wetted parts, the test fluid should be light oil, which is normally the recommended lubricant for the compressor train. The test period is the length of time needed to inspect for leaks, or a minimum ol thirty minutes. Acceptance is based on the lack of leaks as visually observed or the lack of a drop in the test pressure. 

Maximum Allowable Working Pressure -As defined in the construction codes for pressure vessels, the maximum allowable working pressure depends on the type of material, its thickness, and the service conditions set as the basis for design. The vessel or equipment may not be operated above this pressure, or its equivalent stress at any other metal, temperature. However, ANSI B31.3, Petroleum Refinery Piping Code, permits variations above the maximum allowable working pressure, as follows ... 

The ASTM fired pressure vessels code requires pressure-relief devices to prevent pressures from rising more than 6% above the maximum allowable working pressure. 

Manual Valve - Inadvertent operation of a block valve while the plant is onstream may expose equipment to a pressure that exceeds the maximum allowable working pressure. For the purpose of design, it is considered that only one manual valve is opened or closed and control devices are in their normal design position. A PR valve is required if the block valve is not locked or car sealed in the open position and if closure of such valve can result in overpressure. 

The code stipulates that when multiple valves are used, only one of them needs to be set at the maximum allowable working pressure (MAWP). The additional valves can be set at up to 105% of the MAWP. For design purposes the maximum allowable working pressure is assumed to be the same as the design pressure. 

Thus, the maximum allowable back pressure is 10 percent of the maximum allowable working pressure of the vessel. 

Pilot-operated valves have a pilot valve combined with the main valve. The spring of the main valve provides 75 percent loading on the disk and the remaining 25 percent is offered by the gas or vapor through the pilot valve. When the vessel reaches the maximum allowable working pressure, the pilot valve relieves the gas pressure, which contributes to the disk load. Thus the safety valve becomes wide open. This is illustrated in Figure 18. 

Maximum Allowable Working Preaeure or Design Pressure (Hydrotest at 150)... 

A 3,500-gal reaetor with styrene monomer undergoes adiabatie polymerization after being heated inadvertently to 70°C. The maximum allowable working pressure (MAWP) of the reaetor is 5 bar absolute. Determine the relief vent diameter required. Assume a set pressure of 4.5 bara and a maximum pressure of 5.4 bara. Other data and physieal properties are given as follows [12] ... 

Maximum Allowable Working Pressure (MAWP) The maximum allowed pressure at the top of the vessel in its normal operating position at the operating temperature specified for that pressure. 

Like all pressure vessels, the cylinder has a maximum allowable working pressure (MAWP). The maximum allowable working pressure of the cylinder determines the setting of the relief valve that is downstream of the cylinder. The MAWP of the cylinder should be a minimum of 10% or 50 psi greater than its operating pressure. 

The design pressure for a vessel is called its Maximum Allowable Working Pressure (MAWP). In conversation this is sometimes referred to simply as the vessel s working pressure, The MAWP determines the setting of the relief valve and must be higher than the normal pressure of... 

P = maximum allowable working pressure, psig r = inside radius before corrosion allowance is added, in. d = inside diameter before corrosion allowance is added, in. 

The primary protection for high temperature, which could lower the maximum allowable working pressure below the PSV setting, is a high-temperature sensor (TSH), which shuts in the inlet or the source of heat. Back-up protection is provided by leak detection devices. 

Each input source is protected by a PSV set no higher than the vessel s maximum allowable working pressure, and at least one of these PSVs cannot be isolated from the vessel. 

Maximum allowable working pressure MAWP) Highest pressure to which the system can be subjected during operation. Thus, pressure is established by a relief device set pressure and must be less than or equal to the material strength limitations of equipment. This pressure e.stabli.sh-es piping class for fittings and pipe wall thickness requirements, both of which are discussed in Volume 1. 

If more than one standard pipe size is indicated, calculate the wall thickness for each standard pipe size based on required maximum allowable working pressure and select a standard wall thickness for each -Size. 

In accidental releases, pressure within a vessel at time of failure is not always known. However, depending on the cause of vessel failure, an estimate of its pressure can be made. If failure is initiated by a rise in initial pressure in combination with a malfunctioning or inadequately designed pressure-relief device, the pressure at rupture will equal the vessel s failure pressure, which is usually the maximum allowable working pressure times a safety factor. For initial calculations, a usual safety factor of four can be applied for vessels made of carbon steel, although higher values are possible. (The higher the failure pressure, the more severe the effects.)... 

Overpressure pressure increase over the set pressure of the primary relieving device is overpressure. It is the same as accumulation when the relieving device is set at the maximum allowable working pressure of the vessel [10]. 

Maximum Allowable Working Pressure (MAWP) the maximum pressure pounds per square inch gauge permissible at the top of a completed vessel in its operating position for a specific designated temperature corresponding to the MAWP pressure. This pressure is calculated in accordance with the ASME code (Par. UG-98) [1] for all parts or elements of the vessel using closest next larger to calculated value nominal thickness (closest standard for steel... 

The maximum allowable working pressure is equal to or greater than the design pressure for a coincident design temperature. 

Maximum allowable working pressure or design pressure (see Note 3)... 

The margin between the maximum allowable working pressure and the operating pressure must be considered in the selection of a rupture disk. 

Pressure relief must be adequate to prevent internal pressures from rising over 10% above the maximum allowable working pressure, except when the excess pressure is developed by external fire or other unforseen heat source. See design details in later paragraph. Papa [85] proposes an improved technique for relief sizing. Also see Figures 7-7A and 7-7B. 

When a pressure vessel is exposed to external heat or fire, supplemental pressure relieving devices are required for this excessive pressure. These devices must have capacity to limit the overpressure to not more than 21% above the maximum allowable working pressure of the vessel. (See Figures 7-7A and 7-7B.) A single relieving device may be used to handle the capacities of paragraph UG-125 of the code, provided it meets the requirements of both conditions described. 

Single pressure relief valve installation. Must be set to operate at a pressure not exceeding the maximum allowable working pressure of the vessel (MAWP), Ref [1] Par. UG-134, but may be set to operate at pressures below the... 

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