lethal service quick guide

ASME VIII Div.1

Ing. José Juan Jiménez Alejandro: [email protected]

Lethal Service - Quick GuideServicios deSoldaduraIndustrial

Introductions

Requirements for lethal service are scattered throughVIII-1, the code cases and the interpretations. ASME VIII-1 section UW-2 has most of the requirements for lethalservice. Two definitions of lethal service are provided inUW-2. The second definition is also duplicated in the endnotes:[A] vessel is to contain fluids of such a nature that a verysmall amount mixed or unmixed with air is dangerous tolife when inhaled[.]

Introductions

By "lethal substances" are meant poisonous gases or liquidsof such a nature that a very small amount of the gas or ofthe vapour of the liquid mixed or unmixed with air isdangerous to-life when inhaled. For purposes of thisDivision, this class includes substances of this nature whichare stored under pressure or may generate a pressure ifstored in a closed vessel.It is up to the user to determine if a service is lethal. We atPressure Vessel Engineering do not determine if thevessel service is lethal (but we might have opinionsbased on previous jobs).

ASME VIII-1 Lethal Service Code References

UW-2 Service Restrictions is a very important section for lethal service vessels and must be read in its entirety. A few brief points from UW-2:

UW-2(a) and UW-11(a)(1) - All butt welds shall be 100% radiographed

UW-2(a) - ERW pipe (like some grades of SA-53) is not permitted but interpretation VIII-1-01-118 says it is acceptable if the long seam is fully radiographed

UW-2(a) - Post weld heat treatment is required for CS and Low Alloy

UW-2(a)(1)(a) - Category A welds shall be type 1 only (butt welded with no permanent backing strip)


UW-2(a)(1)(b&c) &Interpretation VIII-1 92-211 -Category B & C welds shall be type 1 or 2 only (butt welded). No slip on flanges! No Figure UW-13.2 Flange or Head to Shell attachments

Interpretation VIII-I-98-23 - Category D welds (typically nozzles) shall be full penetration.

UW-2(a)(1)(c) - Category C joints for stub ends have a long list of requirements

UW-2(a)(2 and 3) - Heat exchangers have a long list of requirements

Read all of UW-2 for more restrictions...


When it has been determined that a vessel is in LethalService, some of the following code sections will apply. Othercode sections might also be required. (List last updated June16 2015 based on the ASME 2013 VIII-1 code edition.)

U-2(a)(2) - The user determines if the service is lethal.UG-16(5)(a) - Air cooled and cooling tower heat

exchanger tube walls to be 1/16" min.UG-24(6) - Casting RT requirements.UG-25(e) - No telltale holes.UG-99(g),(k) - Hydro test visual leak inspection cannot be

waived. Do not paint prior to the hydro test.


UG-100(d)(4) - Pneumatic tests cannot be used forlethal service vessels, but also see code cases 2046-2,2055-2, 2407 regarding pneumatic instead of hydrostatictesting

UG-116(c) - "L" stamping must be added to thenameplate.

UG-120(d)(1) - "lethal service" is added to the datareport

UW-2 - Service Restrictions - main source of info onLethal Service (see lots more from UW-2 below)

UW-11(a)(1) - All shell and head butt welds to be100% RT


Fig UW-13.5 - One possible lap joint stub endconfiguration - see also interpretation BC-79-680 / VIII-80-111

UB-3 - Brazed vessels shall not be usedUCS-6 - Do not use SA-36, 38W or SA-283UCS-79 - PWHT and extreme fiber elongation - read for

rules when heat treatment is requiredUCI-2, UCD-2 Cast iron and ductile cast iron vessels are

not allowed.


UIG-2(c) - Metal parts for graphite vessels are to bedesigned to UIG requirements

UIG-23(b) - Factor of safety for lethal serviceUIG-60 - Lethal serviceUIG-99 - Lethal service pressure testsULW-1 & ULW-26(b)(4) - Layered vessels lethal

restrictions apply to the inner shell and heads only


UHX-19.1(b) - Heat exchanger markingsAppendix 2-5(d) & 2-6 - Maximum Flange Bolt SpacingAppendix 2-14(a) - Mandatory flange flexibilityAppendix 7-1, 7-5 - Steel casting examination for 100%

quality factor Appendix 9-8 - if the jacket does not carry lethal

substances, lethal service restrictions do not apply to it


Appendix 17-2(a) - Dimple jackets will not contain lethal substances

Appendix 35-3(c) & 35-7(d) - Mass production rules Appendix W Table W-3 - Filing out the U forms Appendix KK (note 12) - Filling out User Design

Requirements forms Appendix NN Table NN-6-5 - User or designated again

determines if the contents are lethal End notes 65 - Definition of lethal service

Weld restrictions by category

Special lap joint stub end for lethal service - see also Fig UW-13.3 and Fig 2-4(5) and (6)

All partial penetration nozzles are prohibited

All figure UW-13.2 corner welds are prohibited

No slip on flanges

Code Cases

The following Code Cases refer to lethal service for VIII-1 vessels (2013 edition)

1750-20(g) - A126 not to be used for prvs, or rupture disks.

2249 - Furnace Brazing2318 - slip on flanges in lethal service 2321-1 PWHT of P4 and P5A materials 2324 - Ultrasonic inspection2334 - single fillet lap joint tubesheet to shell connection 2346-1 & 2537 - Alternative rules for SE and F&D head

to shell attachment

Code Cases

2369 - Testing of covers separate from vessels 2377 - RT of SA-612 steel 2421 - Single fillet joints in Heat exchanger tubes 2437 - Diffusion bonded heat exchangers2527 – Pneumatic testing of UM vessels 2537 – alternative F&D and SE head to shell

attachment is not for lethal service 2621 – Diffusion bonding2751 – alternative spherical head to shell attachment

is not for lethal service

Interpretations

With interpretations now available on line at cstools.asme.org/Interpretation/SearchInterpretation.cfm it is now easier to find relevant and up to date interpretations. A search for "BPV Section VIII Div 1" keyword: "lethal" returns 44 records. The comments on the most interesting lethal service interpretations are listed below. Refer to the actual interpretations for the actual text.

VIII-1-01-118 and VIII-1-83-77R - ERW pipe may only be used if the long seam is radiographed

VIII-82-65 - volumetric examination of category D joints is not always required

Interpretations

VIII-1-01-42 and VIII-1-04-48 - cone >30° and andcorner joints not permitted

VIII-1-86-84 and VIII-1-95-138 - prohibited flange attachments - Fig UW-13.2(m) and Fig 2-4 sketches (7), (8), (8a), (8b), and (9)

VIII-1-92-112 - full radiography of category C and D butt welds is required except for UW-11(a)(4)

VIII-1-92-194 - full penetration angle joints are not permitted

VIII-1-92-211 - Fig UW-13.2 attachments are not permissible

Interpretations

VIII-1-98-113 - permissible repad and flange padarrangements

VIII-1-98-23 - Fig UW-16.1 (a) and (c) are permissiblenozzle attachments, others are not discussed

VIII-77-62 - "It is the intent of Section VIII, Division 1that Category B and C butt welds in nozzles andcommunicating chambers that neither exceed 10 in.nominal pipe size or 1-1/8 wall thickness are excluded fromthe provisions of radiography, even though the vessel is inlethal service. This overrides the provisions of UW-2(a)."

Interpretations

VIII-80-02 - do not use corner joints from Fig UW-13.2 - redesign to create butt joints that can beradiographed

VIII-80-111 - acceptable lap joint flanges includeFig. 2-4(1) and Fig. UW-13.3 and Fig. 2-4(5) and (6)Disclaimer: This material is provided for educational usesonly. Only ASME can make code interpretations.

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