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MAWP and MAOP 7
- Thread starter Melimelo
- Start date
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4
- #21
Considering all the codes I know, the nearest answer is that MAOP and MAWP are equal as zdas says in the first response. That's why I haven't looked at this since then.
Since these terms are not discussed equally in all codes, some codes ignore MAOP completely, I base that statement on review of B31.3, B31.4, B31.8 and CFR 49 Part 192 TRANSPORTATION OF NATURAL AND OTHER GAS BY PIPELINE and CFR 49 PART 195 TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE,
B31.3 does not define "MAOP"
It defines "design pressure", as follows, and since 302.2.4 defines "design pressure" in terms of yield strength, its clear that "design pressure" is the pressure <= yield. Any condition exceeding this is subject to further incidence counts, time and safety limitations given in the same pp 302.2.4. As such, if those incidence counts, time or safety limits are exceeded, the design pressure must be increased until those overpressure excursions fall under the stated limits, similar to what is mentioned in pp V303.3. Hence overpressure conditions are related back to pressure at yield at a design temperature.
B31.3 uses the term "Operating Pressure", but does not define it. However, since operating pressure must be a condition, it must be <= "design pressure". B31.3 2002 uses the term 3 times, once in conjunction with "maximum permissible normal operating pressure", which is mentioned only to size reinforcement of a branch.
[/quote]
301.2 Design Pressure
301.2.1 General
(a) The design pressure of each component in a
piping system shall be not less than the pressure at the most severe condition of coincident internal or
external pressure and temperature (minimum or maximum)
expected during service, except as provided in
para. 302.2.4.
(b) The most severe condition is that which results
in the greatest required component thickness and the
highest component rating.
~~~~~~~~~~~~~~~~~
302.2.4 Allowances for Pressure and Temperature
Variations. Occasional variations of pressure and/or
temperature may occur in a piping system. Such variations
shall be considered in selecting design pressure
(para. 301.2) and design temperature (para. 301.3). The most severe coincident pressure and temperature shall determine the design conditions unless all of the following criteria are met.
~~~~~~~
(b) Nominal pressure stresses shall not exceed the
yield strength at temperature (see para. 302.3 of this
Code and Sy data in BPV Code, Section II, Part D,
Table Y-1).
[/quote]
B31.3 2002 uses the term "maximum allowable working pressure" in pp 322.6.3 "Pressure Relieving Devices" and sets it equal to "design pressure" for the subsections and defines a few other pressures in the footnotes,
B31.4 Liquid pipeline code
"maximum allowed operating pressure" is used once in pp A451.11 Inspection. It is not otherwise used nor is it specifically otherwise defined.
B31.4 Does define a "maximum steady state operating
pressure" of a piping system be raised to a value
higher than the "internal design pressure", thus design pressure is related to steady state pressure.
Surge pressures are defined as any nonsteady state condition that could exist and are limited to 10% over internal design pressure in ss 402.4
"Operating pressure" is defined as,
B31.8 Gas Transmission Pipeline Code
Design pressure: "is the maximum pressure permitted by this code" (Therefore it obviously must be the maximum of any pressure, operating, allowed, permitted, or otherwise falling under this code.)
805.213 Maximum Operating Pressure (MOP) maximum actual operating pressure, is the highest pressure at which a piping system is operated during a normal operating cycle.
(HERE IT IS MAOP!) 805.214 Maximum allowable operating pressure (MAOP) is the maximum pressure at which a gas system may be operated in accordance with the provisions of this code.
PP 845.214 further defines MAOP in ss 1 in terms of test pressure, the maximum allowable operating pressure shall be limited to the pressure obtained by dividing the test pressure by the class factor.
MAOP do form important safety information that must be submitted by pipeline operators covered by the CFRs and definitions similar to the above can be found in the relavent sections, for which I won't bore you further with endless quotes. There all in here if you're interested,
and,
OK, now that we have all of that, its still very important to note that even though the internal design pressure must produce a stress less than yield, it is not the only condition and must be taken into consideration when establishing operating pressure. It must be considered in combination with other transverse and longitudinal stresses, such that the combined yield stress is not exceeded. Considering that, it is possible that the operating pressure must be reduced to cause a hoop stress of much less than yield stress in certain loading combinations.
BTW, its "only when it is corroded", if a corrosion allowance was used.
**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)
Since these terms are not discussed equally in all codes, some codes ignore MAOP completely, I base that statement on review of B31.3, B31.4, B31.8 and CFR 49 Part 192 TRANSPORTATION OF NATURAL AND OTHER GAS BY PIPELINE and CFR 49 PART 195 TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE,
B31.3 does not define "MAOP"
It defines "design pressure", as follows, and since 302.2.4 defines "design pressure" in terms of yield strength, its clear that "design pressure" is the pressure <= yield. Any condition exceeding this is subject to further incidence counts, time and safety limitations given in the same pp 302.2.4. As such, if those incidence counts, time or safety limits are exceeded, the design pressure must be increased until those overpressure excursions fall under the stated limits, similar to what is mentioned in pp V303.3. Hence overpressure conditions are related back to pressure at yield at a design temperature.
B31.3 uses the term "Operating Pressure", but does not define it. However, since operating pressure must be a condition, it must be <= "design pressure". B31.3 2002 uses the term 3 times, once in conjunction with "maximum permissible normal operating pressure", which is mentioned only to size reinforcement of a branch.
[/quote]
301.2 Design Pressure
301.2.1 General
(a) The design pressure of each component in a
piping system shall be not less than the pressure at the most severe condition of coincident internal or
external pressure and temperature (minimum or maximum)
expected during service, except as provided in
para. 302.2.4.
(b) The most severe condition is that which results
in the greatest required component thickness and the
highest component rating.
~~~~~~~~~~~~~~~~~
302.2.4 Allowances for Pressure and Temperature
Variations. Occasional variations of pressure and/or
temperature may occur in a piping system. Such variations
shall be considered in selecting design pressure
(para. 301.2) and design temperature (para. 301.3). The most severe coincident pressure and temperature shall determine the design conditions unless all of the following criteria are met.
~~~~~~~
(b) Nominal pressure stresses shall not exceed the
yield strength at temperature (see para. 302.3 of this
Code and Sy data in BPV Code, Section II, Part D,
Table Y-1).
[/quote]
B31.3 2002 uses the term "maximum allowable working pressure" in pp 322.6.3 "Pressure Relieving Devices" and sets it equal to "design pressure" for the subsections and defines a few other pressures in the footnotes,
B31.4 Liquid pipeline code
"maximum allowed operating pressure" is used once in pp A451.11 Inspection. It is not otherwise used nor is it specifically otherwise defined.
B31.4 Does define a "maximum steady state operating
pressure" of a piping system be raised to a value
higher than the "internal design pressure", thus design pressure is related to steady state pressure.
Surge pressures are defined as any nonsteady state condition that could exist and are limited to 10% over internal design pressure in ss 402.4
"Operating pressure" is defined as,
B31.8 Gas Transmission Pipeline Code
Design pressure: "is the maximum pressure permitted by this code" (Therefore it obviously must be the maximum of any pressure, operating, allowed, permitted, or otherwise falling under this code.)
805.213 Maximum Operating Pressure (MOP) maximum actual operating pressure, is the highest pressure at which a piping system is operated during a normal operating cycle.
(HERE IT IS MAOP!) 805.214 Maximum allowable operating pressure (MAOP) is the maximum pressure at which a gas system may be operated in accordance with the provisions of this code.
PP 845.214 further defines MAOP in ss 1 in terms of test pressure, the maximum allowable operating pressure shall be limited to the pressure obtained by dividing the test pressure by the class factor.
MAOP do form important safety information that must be submitted by pipeline operators covered by the CFRs and definitions similar to the above can be found in the relavent sections, for which I won't bore you further with endless quotes. There all in here if you're interested,
and,
OK, now that we have all of that, its still very important to note that even though the internal design pressure must produce a stress less than yield, it is not the only condition and must be taken into consideration when establishing operating pressure. It must be considered in combination with other transverse and longitudinal stresses, such that the combined yield stress is not exceeded. Considering that, it is possible that the operating pressure must be reduced to cause a hoop stress of much less than yield stress in certain loading combinations.
BTW, its "only when it is corroded", if a corrosion allowance was used.
**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)
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