MAWP AND MDMT CALCULATIONS.docx

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CALCULATIONS TO DETERMINE THE MAXIMUM ALLOWABLE WORKING

PRESSURE (MAWP) FOR PRESSURE VESSELS (TANKS 1 AND 2)

IN ACCORDANCE WITH API510 TENTH EDITION 2014; PRESSURE VESSEL

INSPECTION CODE IN!SERVICE INSPECTION" RATING REPAIR AND

ALTERATION

SECTION #$% Maximum Allowable Working Pressure (MAWP) Determination

The MAWPfor the continued service of a pressure vessel shall be based on the

computations that are determined using the latest applicable edition of the ASME code or the

construction code to which the vessel was built.

The resulting MAWPfrom these computations shall not be greater than the original MAWP

unless a rerating is performed.

The wall thickness used in these computations shall be the actual thickness as determined

by inspection when multiple thickness measurement shall be taken.

SECTION ! E"aluation o# Existing E$ui%ment wit& Minimal Do'umentation

For pressure vessel that has no name plate and minimal or no design and construction

documentation, the following steps maybe used to verify operating integrity

!. "erform inspection to determine condition of the vessel and determine minimum

thickness values and ade#uacy of the design of the vessel

$. %efine design parameters&. "erform design calculations based on applicable codes and standards'. %o not use allowable stress values of current ASME code (based on design factor of

&.)*+ for older vessels allowable stress values have been based on a design factor

'. to ).! For carbon steel, use allowable stress values for SA*+, -ra.e Cand/oint

e##i'ien'0 o# 1! #or t0%e No!2-. Attach a name plate or stamping showing MA", M%MT, Material Specification,

%ate, etc, (as deemed necessary by the owner/user*0. "erform pressure test as soon as practical as re#uired by code or at the discretion of

the owner/user

ASME 3OI4E5 AND P5ESS65E 7ESSE4 CODE8 SECTION 7IIIDI7ISION I8

564ES 9O5 T:E CONST56CTION O9 P5ESS65E 7ESSE4S

S63SECTION A

6-2 SCOPE

The re#uirements of part 12 in the ASME code are applicable to all pressure vessel and

vessel parts and shall be used in con3unction with the specific re#uirements in subsection 4

and 5 and the mandatory Appendi6 that pertain to the method of fabrication and the materialused.

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6-; MATE5IA4S

(a* Materials sub3ect to stress due to pressure shall conform to one of the specification

given in ASME 4"75 section 88, "art %, subpart 8, Tables 8A, 84, and &, including all

applicable notes in the tables, and shall be limited to those that are permitted in the

applicable part of subsection 5, e6cept as otherwise permitted in 129:, 129!, 129!!, 129!), "art 15S, "art 182 and the mandatory appendices.

6-2< DESI-N

MINIM6M T:IC=NESS O9 P5ESS65E 5ETAININ- COMPONENTS

E6cept for special provisions, the minimum thickness permitted for shells and heads after

forming and regardless of product form and material, shall be 2>2API 21

P Internal Design Pressure

51 Outsi.e ra.ius o# s&ell 'ourse un.er 'onsi.eration

t Minimum t&i'kness o# s&ell 'ourse

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S Maximum allowable stress "alue

S8Ma6imum allowable stress value+ 129$&+ this is the ma6imum unit stress permitted in a

given material used in a vessel constructed under these rules. The ma6imum allowable

tensile stress values permitted for different materials are given in S14"Ao.!+ 2roup

>o.!+ >ominal 5omposition C carbon steel9 "late.

MA@IM6M A44OWA34E ST5ESS 7A46ES S F DI99E5ENT MDMT

MDMT(OC) S (M%a)

9& 9 '=5 !;Mpa

-)=5 !;Mpa

!=5 !;Mpa

!$)=5 !;Mpa

!)=5 !;Mpa

$=5 !;Mpa

$)=5 !;Mpa

&=5 !0Mpa

&$)=5 !'Mpa

&)

=

5 !!Mpa

MA@IM6M TEMPE5AT65E 4IMIT ,;, O C

Therefore, we shall take a value of 9&=5 for our M%MT and our DS value shall be !;Mpa.

From 129$&+ the ma6imum allowable stress value DS that are to be used in the calculations

are to be taken from the tables at the temperature that is e6pected to be maintained in the

metal under the conditions of loading being considered.

MAWP CA4C64ATIONS8 9O5 P5ESS65E 7ESSE4 (TAN= 2)

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E .0

S !;Mpa


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E .0

S !;Mpa

51G 1!;t

P 21+H111H111 @ 1! @ +!>;!; G 1!; @ +!

P

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