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Comparison of EEMUA 159 to API Standards Mark A. Baker, P.E. National Petroleum Management Associations Petro 2012 May 28 – 31, 2012 Washington D.C.

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Presentation on theme: "Comparison of EEMUA 159 to API Standards Mark A. Baker, P.E. National Petroleum Management Associations Petro 2012 May 28 – 31, 2012 Washington D.C."— Presentation transcript:

1 Comparison of EEMUA 159 to API Standards Mark A. Baker, P.E. National Petroleum Management Associations Petro 2012 May 28 – 31, 2012 Washington D.C.

2 EEMUA 159 Users Guide to the Inspection, Maintenance and Repair of Aboveground Vertical Cylindrical Steel Storage Tanks 2 Edition: 3rd Engineering Equipment and Materials Users Association / Jan-2003 / Amendments Feb-2004

3 API Standard 653 Tank Inspection, Repair, Alteration, and Reconstruction Fourth Edition April 2009 Addendum 1, August 2010 Addendum 2, January

4 API Standard 653 This document addresses: Tanks built to API 650 and its predecessor API 12C. Minimum requirements for maintaining the integrity This standard employs the principles of API 650 Owner/operators may apply this standard to any tank constructed to a tank specification. 4

5 EEMUA 159 This Standard addresses: Establishment of essential inspection requirements for tanks. Minimize problems and extend useful life. Gives guidance on design features, common problems experienced during operation and on repair methods. This addresses tanks built in accordance with British Standards Where appropriate it refers to and makes use of international standards and codes such as those from API. This publication is intended as a general inspection, maintenance and repair guide applicable tanks 5

6 Inspector Qualifications API 653 Authorized inspector Must have experience and pass a written examination Recertification is required every 6 years Owner/Operator Inspectors Must have knowledge tanks and local operating conditions EEMUA 159 No certification process for tank inspectors Inspectors should be experienced 6

7 Inspection Requirements Routine External Inspections API 653: Required to be conducted on a Monthly Basis EEMUA 159: Required to be conducted on every 3 Months 7

8 Inspection Requirements Formal External Inspections API 653: Required to be conducted the lesser of 5 years or the quarter corrosion rate life of the shell. 8

9 Inspection Requirements Formal External Inspections EEMUA 159: Ranges from 1 year to 15 year intervals. Factors include climate and type of product.. 5 years – crude oil, and refined products with no internal liner 8 years finished products with internal liner 10 years for Jet A with internal liner 9

10 Table B

11 Inspection Requirements Formal Internal Inspections API 653: Based on the bottom corrosion rate not to exceed 20 years Risk based inspection can be used – See API 580, Risk-Based Inspection. MRT is: for with no RPB or thick film liner when RPB or Thick film liner is present MRT = (Minimum of RTbc or RTip) – Or (StPr + UPr) where: MRT = minimum remaining thickness at the end of interval Or. Or = in-service interval of operation (years to next internal inspection) RTbc = minimum remaining thickness from bottom side corrosion after repairs, RTip = minimum remaining thickness from internal corrosion after repairs, StPr = maximum rate of corrosion not repaired on the top side. UPr = maximum rate of corrosion on the bottom side. 11

12 Inspection Requirements Formal Internal Inspections EEMUA 159: Based on Table B.3 Ranges from 3 years to 20 year intervals. Factors include climate and type of product. 8 years – crude oil 16 years finished products with internal liner 10 years finished products with no liner Allows for use of probabilistic preventive maintenance – detailed explanation and guidelines are given. MRT at next inspection 2.5 mm or 1.5 mm 12

13 Inspection Requirements Formal Internal Inspections EEMUA 159: 13

14 Bottom Extension API 653 requires a minimum thickness of inches at 3/8 inch from the shell- to-bottom weld. EEMUA 159 requires a minimum of 2.5 mm (0.098 in) at 9.5 mm (0.374 in) from the shell-to-bottom weld Approximately the same requirements for each document. 14

15 Inspection Requirements Inspections Checklists Both API 653 and EEMUA 159 use the same checklists 15

16 Foundation Settlement Differential Settlement API 653 requires a total of D/10 survey locations with a minimum of 8. Tolerances are given as 16 Where: S = maximum permissible deflection inft L = arc length between measurements points in ft YS = yield strength in lb f /in 2 E = Youngs modulus in lb f /in 2 H = tank height in ft

17 Foundation Settlement Differential Settlement EEMUA requires a total of D/10 survey locations with a minimum of 8 with the distance not exceeding 10 m. Tolerances are given as: 100 mm (3.94 inches) between any two points at 10 m intervals Alternatively 17

18 Foundation Settlement Differential Settlement Fixed roof tanks without an internal floating cover 18

19 Foundation Settlement Differential Settlement Floating roof tanks and large fixed roof tanks equipped with internal floating covers of diameters exceeding 40 m 19 Where: S = maximum permissible deflection in mm L = arc length between measurements points in meters YS = yield strength in MPa E = Youngs modulus in MPa H = tank height in meters

20 Foundation Settlement Planar Settlement API 653 does not address planar tilt tolerance EEMUA 159 permits a maximum out-of- verticality should not exceed h/100 20

21 Settlement API 653 Edge Settlement 21

22 Settlement EEMUA 159 Edge Settlement Maximum permissible edge settlement to 125 mm (4.92 in)over 750 mm (29.5 in) If it is exceeded then the tank should be re- leveled 22

23 Settlement API 653 Bottom Depressions Maximum permissible bottom settlement or Bulges is given by: B B = 0.37R Where: B B = maximum height of bulge or depth of local depression, in R = radius of inscribed circle in bulged area or local depression, in ft 23

24 Settlement EEMUA 159 Bottom Depressions Depressions are acceptable provided The aspect ratio of height to width of the ripple is not greater than 75:500 (mm:mm) i.e – (3:20) They do not form a severe crease over any of their length 24

25 Settlement Center-to-Edge Settlement (Sagging) API 653 – Does not directly address the overall center-to-edge settlement EEMUA 159 – The maximum settlement is given as 25

26 Shell Thickness API

27 Shell Thickness EEMUA 159 The procedure for evaluation of t min is essentially the same as API 653. EEMUA adds a term for internal pressure which is not considered in API

28 Shell Thickness API 653 allows for the authorized inspector to determine the number and location of UT measurements during an inspection EEMUA 159 requires a grid system for obtaining UT measurements 28

29 Roof Thickness API 653 Min of in. in any 100 in2 area Structure corrosion is to be evaluated EEMUA 159 Min of 2 mm in a 500 mm by 500 mm area (0.079 in. in in2 area) Structure corrosion is limited to 25% before replacement is required. 29

30 Brittle Fracture API 653 Assessment per Section 5 of API 653 EEMUA 159 No specific guidance for brittle fracture considerations 30

31 Repairs API 653 Comprehensive repair section for the tank shell and bottom including nondestructive examination Section 8 – Design Considerations for Reconstructed Tanks Section 9 – Tank Repair and Alteration Section 10 – Dismantling and Reconstruction Section 12 – Examination and Testing 31

32 Repairs EEMUA 159 The document provides minimal guidance to the user. The document refers the user to international standards Appendix C has some examples for welding sequence and tank jacking 32

33 Hydrostatic Testing API 653 Comprehensive section detailing when a hydrostatic test is required Provides calculation for maximum fill level Provides rules for foundation settlement surveys when settlement is anticipated. 33

34 Hydrostatic Testing EEMUA 159 Provides a detailed filling sequence Water quality requirements Provides a reprint from API 653 as well as discusses the BS 2654 requirements Discusses survey requirements 34

35 Filling Sequence 35

36 36 EEMUA 159 Hydrostatic Test Flow Chart

37 Additional Requirements EEMUA 159 Details not in API 653: Tank painting Cathodic protection Corrosion mechanisms Product characteristics Risk based inspection Tank jacking Detailed foundation design Tank relocation 37

38 Other information Much of the information presented in EEMUA 159 is present in other API standards: Tank painting- API 652 Cathodic protection- API 651 Corrosion mechanisms - API 570 Product characteristics- API 570 Risk based inspection- API 580 Tank jacking- API SCAST studying this issue for inclusion in API 653 Foundation design- API 650 (Appendix B) Tank relocation- API 653 (reconstruction) 38

39 Collaboration No official collaboration between the two standards is underway The Chairman of the EEMUA 159 committee has attended API SCAST meetings Some members of the SCAST committee have attended EEMUA 159 meetings 39

40 Conclusions API 653 and EEMUA 159 are both good documents API 653 provides a procedure to demonstrate that the tank inspector posses a minimum body of knowledge and experience In general, API 653 is more conservative than EEMUA 159 EEMUA 159 contains information which fills in topics not covered in API

41 Thank you Mark A. Baker, P.E. Baker Consulting Group, Inc.


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