Md. Code Regs. 09.12.01.26 – Pressure Vessel — Existing Installation.

A. The maximum allowable working pressure for a standard pressure vessel:
1. (1) Shall be determined in accordance with the ASME Code under which it was constructed and stamped; and
2. (2) May not exceed the pressure shown on the manufacturer's name plate stamp and data report.
B. Nonstandard Pressure Vessel—Maximum Allowable Working Pressure.
1. (1) The maximum allowable working pressure on the shell of a nonstandard pressure vessel shall be determined by the strength of the weakest course computed by multiplying TS by t and E and dividing the product by R multiplied by FS: (TS x t x E)/(R x FS) = maximum allowable working pressure, PSIG, where:
  1. (a) TS = ultimate tensile strength of the shell plate, PSI, which, if unknown, shall be 55,000 PSI for steel, for temperatures not exceeding 700°F;
  2. (b) t = minimum thickness of the shell plate of the weakest course, in inches;
  3. (c) E = efficiency of the longitudinal joint, which is, for:
    1. (i) Riveted joints, the calculated riveted efficiency, and
    2. (ii) Fusion-welded and brazed joints: Single lap weld ... 40 percent Double lap weld ... 60 percent Single butt weld ... 60 percent Double butt weld ... 75 percent Forge weld ... 70 percent Brazed steel ... 80 percent
  4. (d) R = radius of the weakest course of the shell, in inches, using the:
    1. (i) Inside radius, if the thickness is 10 percent or less of the radius, and
    2. (ii) Outside radius, if the thickness is greater than 10 percent of the radius;
  5. (e) FS = factor of safety required by this regulation.
2. (2) The maximum allowable working pressure for a cylindrical nonstandard pressure vessel subjected to external or collapsing pressure shall be determined by the ASME Code, Section VIII, paragraphs UG-28 and UG-29.
3. (3) Factor of Safety.
  1. (a) For an existing installation, the minimum factor of safety shall be at least four.
  2. (b) When necessary to ensure safe operation, the inspector may increase the factor of safety based on the:
    1. (i) Condition of the vessel; and
    2. (ii) Specific service to which it is subject.
4. (4) The maximum allowable working pressure for formed heads under pressure shall be determined by the:
  1. (a) Appropriate formulas from the ASME Code, Section VIII, Division 1, Paragraphs UG-32, UG-33, and UG-35; and
  2. (b) Tensile strength and factors of safety set out in this regulation.
C. If the inspector determines, because of conditions disclosed during an inspection, that the interior or exterior lining, covering, or brickwork should be removed to expose parts of the vessel not normally visible, the owner shall remove the material to permit:
1. (1) Proper inspection; and
2. (2) Drilling any part of the vessel where necessary to ascertain thickness.
D. Safety Appliances.
1. (1) To ensure safe operation, a pressure vessel shall have:
  1. (a) Safety and relief valves; and
  2. (b) Indicating and controlling devices.
2. (2) Safety appliances shall be constructed, located, and installed so that they cannot readily be rendered inoperative.
3. (3) The relief capacity of a safety valve shall be sufficient to prevent pressure in the vessel from rising more than 10 percent above the maximum allowable working pressure, with static head pressure factored into the calculation.
4. (4) Safety valve discharge shall be carried to a safe place.
E. Repairs and replacements of fittings and appliances shall comply with the requirements for new installations.

Authority: Public Safety Article, Title 12, Annotated Code of Maryland
Ch. 351, Acts of 2004

Effective date: October 15, 1975 (2:23 Md. R. 1414)

Regulation .02CC amended and .02DD repealed effective June 1, 1982 (9:8 Md. R. 821)

Regulation .02PP amended effective November 4, 1985 (12:22 Md. R. 2103)

Regulations .07—.08 adopted effective November 4, 1985 (12:22 Md. R. 2103)

Regulations .01—.08 repealed and new Regulations .01—.32 adopted effective June 1, 1989 (16:10 Md. R. 1106)

Regulation .01B amended effective September 1, 1989 (16:16 Md. R. 1749); April 16, 1990 (17:7 Md. R. 848); October 7, 1996 (23:20 Md. R. 1422); June 30, 1997 (24:13 Md. R. 930)

Regulation .01B amended as an emergency provision effective July 14, 1999 (26:16 Md. R. 1237); amended permanently effective October 4, 1999 (26:20 Md. R. 1545)

Regulation .01B amended effective July 10, 2000 (27:13 Md. R. 1211)

Regulation .01-1 amended effective January 31, 1994 (21:2 Md. R. 98); July 18, 1994 (12:14 Md. R. 1228); November 20, 1994 (21:25 Md. R. 1933); July 3, 1995 (22:13 Md. R. 966); January 15, 1996 (23:1 Md. R. 23); April 22, 1996 (23:8 Md. R. 604); August 12, 1996 (23:16 Md. R. 1175); June 30, 1997 (24:13 Md. R. 930); November 3, 1997 (24:22 Md. R. 1551); July 10, 2000 (27:13 Md. R. 1211); February 19, 2001 (28:3 Md. R. 205)

Regulation .01-1A(1) amended as an emergency provision effective July 14, 1999 (26:16 Md. R. 1236); amended permanently effective October 4, 1999 (26:20 Md. R. 1545)

Regulation .01-2 adopted effective October 11, 1993 (20:20 Md. R. 1569)

Regulation .01-2 amended effective June 30, 1997 (24:13 Md. R. 930)

Regulation .02A amended effective October 7, 1996 (23:20 Md. R. 1422); July 10, 2000 (27:13 Md. R. 1211); February 19, 2001 (28:3 Md. R. 205)

Regulation .03B amended effective July 3, 1995 (22:13 Md. R. 966)

Regulation .09 amended effective March 5, 1990 (17:4 Md. R. 496)

Regulation .14G adopted effective October 11, 1993 (20:20 Md. R. 1569)

Regulation .15 amended effective September 3, 1990 (17:17 Md. R. 2078)

Regulation .17A amended effective October 11, 1993 (20:20 Md. R. 1569)

Regulation .17A amended as an emergency provision effective July 14. 1999 (26:16 Md. R. 1237); amended permanently effective October 4, 1999 (26:20 Md. R. 1545)

Regulation .17E amended effective September 1, 1989 (16:16 Md. R. 1749)

Regulation .22B amended effective July 3, 1995 (22:13 Md. R. 966)

Regulation .25B amended as an emergency provision effective July 14, 1999 (26:16 Md. R. 1237); amended permanently effective October 4, 1999 (26:20 Md. R. 1545)

Regulation .26B amended effective July 3, 1995 (22:13 Md. R. 966)

Regulation .27 amended as an emergency provision effective July 14, 1999 (26:16 Md. R. 1237); amended permanently effective October 4, 1999 (26:20 Md. R. 1545)

Regulation .27B amended effective August 5, 1991 (18:15 Md. R. 1725); November 20, 1994 (21:23 Md. R. 1933)

Regulation .27C adopted effective August 5, 1991 (18:15 Md. R. 1725)

Regulation .27C amended effective October 11, 1993 (20:20 Md. R. 1569)

Regulation .28A amended effective June 30, 1997 (24:13 Md. R. 930)

Regulation .31D amended effective November 20, 1994 (21:23 Md. R. 1933)

Regulation .32 amended and recodified to Regulation .01-1 effective October 11, 1993 (20:20 Md. R. 1569)

Regulation .32A amended effective April 16, 1990 (17:7 Md. R. 848)

Regulation .33 adopted effective September 1, 1989 (16:16 Md. R. 1749)

Regulation .33A amended, B repealed effective June 30, 1997 (24:13 Md. R. 930)

Regulation .34 adopted effective June 30, 1997 (24:13 Md. R. 930)

Chapter revised as an emergency provision effective August 10, 2001 (28:17 Md. R. 1551); revised permanently effective November 12, 2001 (28:22 Md. R. 1936)

Regulation .01B amended effective December 12, 2002 (29:24 Md. R. 1919); April 23, 2018 (45:8 Md. R. 419)

Regulation .01-1 amended effective April 19, 2021 (48:8 Md. R. 308)

Regulation .01-1A amended effective September 29, 2003 (30:19 Md. R. 1331); March 17, 2014 (41:5 Md. R. 342)

Regulation .01-1A, B amended effective September 2, 2002 (29:17 Md. R. 1380)

Regulation .01-1A, C amended effective April 23, 2018 (45:8 Md. R. 419)

Regulation .01-1B, C amended effective December 12, 2002 (29:24 Md. R. 1919)

Regulation .01-2 amended effective December 12, 2002 (29:24 Md. R. 1919); April 23, 2018 (45:8 Md. R. 419)

Regulation .03B, C amended and D adopted effective September 30, 2002 (29:19 Md. R. 1523)

Regulation .08 amended effective April 23, 2018 (45:8 Md. R. 419)

Regulation .09 amended effective April 23, 2018 (45:8 Md. R. 419)

Regulation .14 recodified to Regulation .14-1 and new Regulation .14 adopted as an emergency provision effective July 9, 2004 (31:18 Md. R. 1348); adopted permanently effective September 27, 2004 (31:19 Md. R. 1431)

Regulation .14C amended effective April 23, 2018 (45:8 Md. R. 419)

Regulation .14D adopted effective April 23, 2018 (45:8 Md. R. 419)

Regulation .14-1G amended effective April 23, 2018 (45:8 Md. R. 419)

Regulation .15B amended effective April 23, 2018 (45:8 Md. R. 419)

Regulation .16 amended as an emergency provision effective December 22, 2008 (36:2 Md. R. 96); emergency status extended at 36:17 Md. R. 1310; emergency status expired November 19, 2009

Regulation .16 amended effective April 23, 2018 (45:8 Md. R. 419)

Regulation .16-1 adopted as an emergency provision effective December 22, 2008 (36:2 Md. R. 96); emergency status extended at 36:17 Md. R. 1310; emergency status expired November 19, 2009

Regulation .16-1 adopted effective December 26, 2011 (38:26 Md. R. 1696)

Regulation .16-1 amended effective April 23, 2018 (45:8 Md. R. 419)

Regulation .17 amended effective April 23, 2018 (45:8 Md. R. 419)

Regulation .17C amended effective December 12, 2002 (29:24 Md. R. 1919)

Regulation .19 repealed and new Regulation .19 adopted effective April 23, 2018 (45:8 Md. R. 419)

Regulation .27A amended effective September 29, 2003 (30:19 Md. R. 1331); April 23, 2018 (45:8 Md. R. 419)

Regulation .27C adopted effective April 23, 2018 (45:8 Md. R. 419)

Regulation .28 amended effective April 23, 2018 (45:8 Md. R. 419)

Regulation .28G amended effective July 16, 2020 (47:14 Md. R. 675)

Regulation .28-1 amended effective April 23, 2018 (45:8 Md. R. 419)

Regulation .28-2B, F amended effective April 23, 2018 (45:8 Md. R. 419)

Regulation .28-3 amended effective April 23, 2018 (45:8 Md. R. 419)

Regulation .29 amended effective April 23, 2018 (45:8 Md. R. 419)

Regulation .34 amended effective April 23, 2018 (45:8 Md. R. 419)

Regulation .35 amended effective April 23, 2018 (45:8 Md. R. 419)

Regulation .37 adopted effective December 12, 2002 (29:24 Md. R. 1919)

Regulation .38 adopted effective December 12, 2002 (29:24 Md. R. 1919)