Lethal Service

Figure UW-3

Note: This reference information is provided for your convenience only. You are responsible for complying with all ASME Section VIII, Division 1 & 2 lethal service requirements. We are not offering engineering advise nor engineering services here and accept no liability whatsoever for use of this information.

Code Cases Referring to Lethal Service.

Interpretations Referring to Lethal Service   ASME Interpretations Database - Search Tool

Lethal Service Graphite Design Requirements

Lethal Service Flange Design Requirements

Definition of Lethal Service / Substance: Poisonous gases (or vapors of liquids, or vapors mixed with air) which are dangerous to life when inhaled in small quantities.

Lethal Vessels: Includes vessels under mechanical pressure and closed vessels which generate vapor pressure due to heating.

Responsibility: ASME requires the end user or designated agent (not the contractor or fabricator) to specify when lethal service is required.

U-2(a)(2): The end user or designated agent (not the contractor or fabricator) must specify when lethal service is required.

UG-16(b)(5)(a): Air cooled and cooling tower heat exchanger tube walls must be 1/16" minimum thickness.

UG-24(a)(6): Casting requirements.

     UCI-2, UCD-2: Castings of cast iron and cast ductile iron are not allowed.

          Appendix 7-1: Examinations per Appendix 7 is mandatory for steel castings.

UG-25(e): Telltale holes not allowed on pressure boundary parts (shells, heads, nozzle necks, etc.)

     Interpretation VIII-1-16-42: UG-37(g) telltale holes are required in (outside) reinforcement plates and nozzle saddles.

     ULW-76: Telltale hole required for layered vessels.

          ULW-1: Lethal requirements apply to the inner shell and heads only.

UG-99(g): Hydrostatic test visual leak inspection is mandatory.

UG-99(k): Painting and lining prior to hydrostatic test are not allowed.

UG-116(c): Stamp "L" on nameplate.

UG-120(d)(1): Add "Lethal Service" to the ASME data report.

UW-2(a): We recommend reading this entire section carefully. Summary:

     All butt weld joints require full length radiography. [Also UW-11(a)(1), Interpretation VIII-82-65]

     ERW pipe and tube are not allowed for shells or nozzles unless the longitudinal seams are fully radiographed per UW-11(a)(1).

          Interpretations VIII-1-01-118 and VIII-1-83-77R.

          Braun Note: We recommend using seamless pipe & tube.

     Post weld heat treatment (PWHT) is mandatory for carbon and low alloy steels.

     Lap joint stub ends. UW-2(a)(1)(c), Figure UW-13.5, Interpretation VIII-80-111.

     Category A weld seams must be Table UW-12 Type No. 1 only. UW-2(a)(1)(a).

     Category B & C weld seams must be Table UW-12 Type No. 1 or Type No. 2 only. UW-2(a)(1)(b), Interpretation VIII-1-92-211.

     Category D weld seams must be full penetration. UW-2(a)(1)(d), Interpretation VIII-1-98-23.

     Slip-on flanges and Figure UW-13.2 details are not allowed. UW-2(a)(1)(b), Interpretation VIII-1-92-211.

     Heat exchanger tubes. Lethal stamping only one exchanger side. UW-2(a)(2), UW-2(a)(3).

UB-3(a): Brazed construction is not allowed.

UCS-6(b)(1): SA-36, SA/CSA-G40.21 38W, and SA-283-A,B,C,D are not allowed.

UCS-79(d)(1): Heat treatment is mandatory if extreme fiber elongation exceeds 5%.

UHX-19.1(b): Required nameplate markings.

Appendix 9-8(c): If only inner vessel is lethal service, jackets are exempt from lethal service requirements.

Appendix 17-2(a): Dimpled or embossed assemblies are not allowed in lethal service.

Appendix 35-3(c): Mass production. Inspections per UG-90(c)(1) are mandatory.

Appendix 35-7(d): Mass production hydrotest rule.