8" NPS x 285 PSI Vertical Pressure Vessel

ASME Section VIII Div. 1, 2023 Edition | CRN W9112.213 | Registered in Alberta, July 2025

This is a small vertical pressure vessel built and registered for natural gas service in Alberta. The shell is 8.625 inch outside diameter SA-53 Grade B seamless pipe, the top is an SA-234 WPB B16.9 pipe cap, and the bottom is a 0.75 inch SA-516-70 welded flat cover joined to the shell with a UW-13.2 (e-1) detail. Four threaded half-couplings give the vessel its process and instrument connections. The vessel is rated for 285 psi at 650 F with a -20 F design MDMT and a -55 F rated MDMT at full pressure.

Reece Custom Manufacturing designed the vessel in Codeware COMPRESS 2024, certified the calculations under APEGA Permit 15926, and assigned Canadian Registration Number W9112.213. Reference number 14-194-REG. Shop hydrostatic test was performed at 1.3 x MAWP per UG-99(b); a 1.5 x MAWP corroded option is registered for field test if required.

CRN

W9112.213

CODE

ASME VIII Div 1, 2023

DESIGN PRESSURE

285 psi

DESIGN TEMP

650 °F

DESIGN MDMT

-20 °F

RATED MDMT

-55 °F @ 285 psi

MAWP (LIMITED)

285 psi

SHELL

NPS 8 Sch 40 SA-53B

CORROSION ALLOWANCE

0.125″ inner

JOINT EFFICIENCY

0.85 shell, 1.00 cover

EMPTY WEIGHT

158 lb new / 103 lb corr.

TEST WEIGHT

258 lb

Calculation Package and Code Compliance

The five sections below mirror the registered calculation package for CRN W9112.213. Numbers, code clauses, and equations are reproduced from the as-built design record. Personal identifiers, sealing-engineer credentials, and software license details have been removed from the public version.

Design conditions and code edition

Parameter	Value
Code of construction	ASME Boiler and Pressure Vessel Code, Section VIII Division 1, 2023 Edition
Jurisdiction	Alberta, Canada (CRN W9112.213). Reference 14-194-REG
Design pressure (internal)	285 psi
Design temperature	650 °F
Design MDMT	-20 °F
Rated MDMT at full design pressure	-55 °F
MAWP (component-limited by welded cover)	285 psi
Corrosion allowance	0.125 in inner surface, 0 in outer surface
Joint efficiencies	E = 0.85 for shell longitudinal seams (seamless pipe, no RT) per UW-11(c) and Type 1; E = 1.00 for welded cover
Service	Sweet natural gas, vertical orientation, Alberta installation
Design software	Codeware COMPRESS 2024 (Build 8400)
Engineering certification	APEGA Permit 15926, sealed July 8, 2025 by Reece in-house engineering

UG-22 loadings considered

UG-22 of Section VIII Division 1 requires the designer to consider every loading that can act on the vessel. For this vessel the following were evaluated and are recorded in the calculation file:

Internal design pressure of 285 psi at 650 °F.
Static head of test liquid during shop hydrotest (vertical orientation, water at 70 °F).
Self-weight of vessel and contents in the new and corroded conditions.
Wind: not applicable, vessel is supported by external piping and is not free-standing.
Seismic: vessel has no skirt, legs, or lug supports, so seismic calculations were not required (NBC 2020 considered for manufacturer location only).
Reactions from attached piping: covered by the attaching pipe spec rather than vessel design.
Cyclic loading: not a fatigue-screened service.

Material toughness basis

All pressure-retaining materials were screened for low-temperature toughness using UCS-66, with reductions per UCS-66.1. The shell, top cap, straight flange, and all four nozzles fall within the impact-test exemption. The welded cover plate, governed by UCS-66 Curve D, also clears the exemption check. The result is a -55 °F rated MDMT at full design pressure of 285 psi without any impact testing.

Hydrostatic test basis

Two test conditions are registered. The shop test is the standard UG-99(b) case at 1.3 x MAWP corrected for stress ratio. A field corroded test at 1.5 x MAWP is also calculated and registered as an option for in-service retest. Test temperature of 70 °F is above the brittle-fracture floor required by UG-99(h).

Source: registered calculation package 008_0285_0125_+650_-20_V_1 Rev. 1, pages 4 to 5 and 12 to 13.

Each pressure-retaining component was sized for the governing condition per the relevant ASME clause. The shell, top cap straight flange, and three of four nozzles end up governed by UG-16 minimum thickness, not by the pressure equation. The welded bottom cover is the pressure-limiting component at 285 psi MAWP.

Pressure summary by component

Component	Material	Design thickness t (in)	MAWP (psi)	Rated MDMT (°F)	Governing clause
Shell (pipe, NPS 8 Sch 40)	SA-53 Gr B Smls	0.209	536.11	-55	Appendix 1-1
Top: B16.9 pipe cap	SA-234 WPB	0.205	568.10	-55	Appendix 1-4(c)
Top: cap straight flange	SA-234 WPB	0.209	676.33	-55	Appendix 1-1
Bottom: welded flat cover	SA-516-70	0.7072	328.47	-55	UG-34(c)(2), Sketch (h)
N-H-01: 2″ Class 3000 cplg, head, set-through, double fillet	SA-105 (norm.)	0.0171 t_r	543.73	-155	UG-37, UG-41, UG-44
N-S-01: 2″ Class 6000 cplg, shell, set-on, single fillet	SA-105 (norm.)	0.0172 t_r	375.00	-155	UG-37, UG-41, UG-44
N-S-02: 1″ Class 6000 cplg, shell, passes Cat A joint	SA-105 (norm.)	0.0095 t_r	375.00	-155	UG-37, UG-41, UG-44
N-S-03: 3/4″ Class 6000 cplg, shell, set-on, single fillet	SA-105 (norm.)	0.0093 t_r	375.00	-155	UG-37, UG-41, UG-44

The vessel MAWP is limited to 285 psi by the welded cover, even though the shell and cap have substantially more pressure capacity. This is a deliberate choice on small vessels because increasing the cover plate thickness adds cost and welding for no benefit, the cover already meets the 285 psi service requirement.

UG-16(b) governing minimum thickness

For pipe-based components, UG-16(b) requires a minimum wall of 1/16 in plus corrosion allowance. With 0.125 in inner CA, that comes to 0.0938 + 0.125 = 0.2188 in. The shell, cap, and straight flange all clear this floor and the pressure equation drives a thinner number, so UG-16 is the governing condition for those parts.

Hydrotest summary (shop test, UG-99(b))

Component	Local test pressure (psi)	Stress during test (psi)	Allowable test stress (psi)	Stress excessive?
B16.9 pipe cap top (governs UG-99(b) ratio)	370.67	5,433	31,500	No
Straight flange on cap	370.67	4,777	31,500	No
Shell	372.55	5,461	31,500	No
Welded cover bottom	372.55	13,922	51,300	No
1″ cplg N-S-02	372.14	5,270	47,250	No
2″ cplg N-H-01 (head)	370.53	4,723	47,250	No
2″ cplg N-S-01 (shell)	372.38	5,273	47,250	No
3/4″ cplg N-S-03	371.92	5,267	47,250	No

Test gauge pressure at 70 °F = 1.3 x MAWP x LSR = 1.3 x 285 x 1 = 370.5 psi. Field test condition not investigated. Brittle-fracture provision UG-99(h) satisfied because test temperature of 70 °F is above the -25 °F minimum recommended temperature.

Material schedule

Component	Material specification	ASME II-D reference	Notes
Shell	SA-53 Grade B, seamless pipe	II-D Table 1A, p. 16, line 15	NPS 8 Sch 40 (Std), 8.625 in OD x 0.322 in nominal wall
Top cap	SA-234 WPB	II-D Table 1A, p. 16, line 18	ASME B16.9 pipe cap, modified, 0.322 in nominal wall
Welded bottom cover	SA-516 Grade 70	II-D Table 1A, p. 20, line 45	Plate, 0.75 in thick, normalized, fine grain practice
Threaded half-couplings (all four)	SA-105 (normalized)	II-D Table 1A, p. 20, line 31	Class 3000 (head) and Class 6000 (shell)

Nozzle schedule

Tag	Size / Class	Location	Type	Welds	Orientation / offset
N-H-01	NPS 2 Class 3000	Head (top cap)	Threaded half-coupling, set through	Inner and outer fillet (double fillet)	Centered on cap
N-S-01	NPS 2 Class 6000	Shell	Threaded half-coupling, set on	Outer fillet only (single fillet)	0°, 36 in offset to datum
N-S-02	NPS 1 Class 6000	Shell	Threaded half-coupling, set on, passes through Category A joint	Outer fillet (single fillet) plus joint reinforcement	180°, 5 in offset to datum
N-S-03	NPS 3/4 Class 6000	Shell	Threaded half-coupling, set on	Outer fillet only (single fillet)	180°, 18 in offset to datum

All nozzle inside edges rounded per UG-76(c). All nozzle weld throats sized per UW-16 and verified by UG-41 weld failure path analysis.

Radiography summary

Joint	Category	Type	Joint efficiency	RT
Shell longitudinal seam	A	Seamless pipe, Type 1	0.85	None per UW-11(c)
Top: cap to shell circumferential	B	Type 1 butt with one-side weld	0.85	None per UW-11(c)
Bottom: welded cover to shell	C	Figure UW-13.2 sketch (e-1) corner joint	1.00	None required
All nozzle longitudinal seams	A	Seamless half-coupling forging	n/a	None

Dimensional summary

Overall length: shell 52 in plus B16.9 cap straight flange of 1.723 in plus cap dish, plus welded cover thickness of 0.75 in.
Outside diameter at shell: 8.625 in (NPS 8 Sch 40 Std).
Welded cover outside diameter: 10.875 in (cover overhangs the shell to provide the UG-34 weld land).
Cover weld bevel depth: 0.572 in (clears the UW-13.2 minimum of 0.519 in).
Empty weight new: 158 lb. Empty weight corroded: 103 lb. Test weight (water filled): 258 lb.

The registered calculation file performs the following code checks. Each one is a discrete pass/fail item in the design record and is reproducible from the inputs in Section 1.

Pressure-retaining wall thickness

UG-27(c)(1) circumferential stress for cylindrical shells. Shown as the Appendix 1-1 outside-diameter form for radii Ro greater than 0.5 R.
Appendix 1-1 alternative thickness equations on the outside diameter basis. Used for the shell and the cap straight flange.
Appendix 1-4(c) for the B16.9 pipe cap dish, with the K factor calculated from inside diameter and dish height in both new and corroded conditions.
UG-32 formed-head requirements (referenced for the cap geometry check).
UG-34(c)(2) with Sketch (h) for the welded flat cover, using factor C = 0.33 from Figure UG-34.
UG-34(d) dimensional checks: shell wall ts greater than or equal to 1.25 t_r.
UG-16(b) minimum wall thickness, 1/16 in plus corrosion allowance, applied to all pressure-retaining components.

Nozzle and opening reinforcement

UG-37 area-replacement reinforcement check for each of N-H-01, N-S-01, N-S-02, N-S-03. Each nozzle reports A_required, A_available, A₁, A₂, A₃, A₅, A_welds.
UG-40 limits of reinforcement parallel and normal to the vessel surface.
UG-41 weld failure path analysis. Three paths checked per nozzle: weld load W, path 1-1 strength, path 2-2 strength.
UG-44 external loads on small connections, all four nozzles cleared by inspection.
UG-45 minimum nozzle neck thickness check for each connection.
UG-76(c) requirement to round inside edges of openings.

Welds and joint design

UW-11(c) radiography exemption for Type 1 butt joints in lethal/severe service categories not invoked here.
UW-13.2 sketch (e-1) detail for the welded flat cover to shell joint, including bevel depth and outer fillet leg.
UW-16 weld sizing for nozzle attachment fillets. All four nozzle fillets sized at Leg41 = 0.2188 in throat.

Toughness and brittle fracture

UCS-66 base MDMT screening from Curves A through D for each material.
UCS-66.1 reduction in MDMT based on stress ratio t_rE* / (t_n – c).
UCS-66(b)(3) stress-ratio path used for the threaded couplings to drop their rated MDMT to -155 °F at the design pressure.
UCS-68(c) cold-bending exemption check (not triggered here, no cold-formed parts).

Hydrostatic test

UG-99(b) shop hydrostatic test at 1.3 x MAWP, corrected by the lowest stress ratio of the components. The B16.9 pipe cap governs the stress ratio at 1.0000 (all others 1.0638 to 1.1236).
UG-99(h) brittle-fracture provision: minimum test temperature of -25 °F. Shop test at 70 °F passes by 95 °F margin.
UG-99(l) note for custom flange assemblies (not applicable, no flanges on this vessel).
Field corroded test option calculated at 428 psi (1.5 x MAWP basis), all components clear with stress less than allowable test stress.

Marking and registration

UG-116 nameplate marking content.
Canadian Registration: CRN W9112.213, jurisdiction Alberta. Reference 14-194-REG.

Deficiencies: none. Every clause checked passes with margin. The pressure-limiting item is the welded bottom cover (328.47 psi MAWP), and the toughness-limiting item is the welded cover at -55 °F rated MDMT.

The four examples below are pulled from the registered calculation package and show the actual numbers used to register CRN W9112.213. Each one shows the input, the equation, the substitution, and the result.

Example 1. Shell wall thickness and MAWP, Appendix 1-1

NPS 8 Sch 40 SA-53 Grade B seamless pipe, 8.625 in OD, 0.322 in nominal wall, 0.85 joint efficiency, 0.125 in inner corrosion allowance.

Inputs: P = 285 psi, R_o = 4.3125 in, S = 17,100 psi (SA-53B at 650 °F), E = 0.85, c = 0.125 in.

Required thickness:

t = (P x Ro) / (S x E + 0.40 x P) + Corrosion t = (285 x 4.3125) / (17,100 x 0.85 + 0.40 x 285) + 0.125 t = 0.0839 + 0.125 = 0.209 in

UG-16(b) check: 1/16 + c = 0.0938 + 0.125 = 0.2188 in. Governs over the pressure equation.

MAWP at 650 °F (corroded, with mill tolerance 0.875):

P = (S x E x t) / (Ro – 0.40 x t) – Ps P = (17,100 x 0.85 x (0.322 x 0.875 – 0.125)) / (4.3125 – 0.40 x (0.322 x 0.875 – 0.125)) – 0 P = 536.11 psi

The shell carries about 1.88 times the design pressure in the corroded condition. UCS-66 stress ratio = (0.0839 x 0.85) / (0.2818 – 0.125) = 0.455, which gives a 68.9 °F reduction from the Curve B exemption temperature of -20 °F, so the rated MDMT is -55 °F (limited by the -55 floor).

Example 2. B16.9 pipe cap, Appendix 1-4(c)

SA-234 WPB, NPS 8 Sch 40 cap modified, dish height h = 1.9953 in (new) or 2.1203 in (corroded), inside diameter D = 7.981 in (new) or 8.231 in (corroded).

Geometry factor K (corroded):

K = (1/6) x [2 + (D / (2 x h))^2] K = (1/6) x [2 + (8.231 / (2 x 2.1203))^2] K = 0.9613

Required thickness, corroded at 650 °F:

t = (P x Do x K) / (2 x S x E + 2 x P x (K – 0.1)) + Corrosion t = (285 x 8.625 x 0.961276) / (2 x 17,100 x 0.85 + 2 x 285 x (0.961276 – 0.1)) + 0.125 t = 0.2049 in

MAWP, corroded at 650 °F:

P = (2 x S x E x t) / (K x Do – 2 x t x (K – 0.1)) – Ps P = (2 x 17,100 x 0.85 x (0.875 x 0.322 – 0.125)) / (0.961276 x 8.625 – 2 x (0.875 x 0.322 – 0.125) x (0.961276 – 0.1)) P = 568.10 psi

The cap is governed by UG-16 minimum thickness (0.2188 in), not by the pressure equation, so the wall used in fabrication is the standard cap thickness of 0.322 in.

Example 3. Welded flat cover, UG-34(c)(2) Sketch (h) with UW-13.2 (e-1) weld

SA-516 Grade 70 plate, 0.75 in nominal thickness, normalized and fine-grain practice, attached to NPS 8 shell with the corner-joint detail of Figure UW-13.2 sketch (e-1).

Inputs: d = 8.231 in (corroded ID), C = 0.33 from Figure UG-34 sketch (h), S = 18,800 psi, E = 1.00, P = 285 psi.

Required thickness:

t = d x sqrt(C x P / (S x E)) + Corrosion t = 8.231 x sqrt(0.33 x 285 / (18,800 x 1)) + 0.125 t = 0.7072 in

MAWP at 650 °F:

MAWP = (S x E / C) x (t / d)^2 – Ps MAWP = (18,800 x 1 / 0.33) x (0.625 / 8.231)^2 – 0 MAWP = 328.47 psi

UW-13.2 weld sizing:

a >= 2 x ts + Ci,shell + Co,shell / 0.7 a >= 2 x 0.197 + 0.125 + 0 / 0.7 a >= 0.519 in. Bevel depth provided = 0.572 in. OK.

UG-34(d) check: ts = 0.197 in ≥ 1.25 x t_r = 1.25 x 0.0714 = 0.0892 in. OK. UCS-66 Curve D gives a 0.8156 stress ratio and 18.4 °F reduction, so the cover is exempt from impact testing at the -20 °F design MDMT, with a -55 °F rated MDMT at full pressure.

Example 4. Nozzle reinforcement, N-S-03 (3/4 inch Class 6000 coupling)

SA-105 normalized threaded half-coupling, 1.05 in inside diameter, 0.35 in nominal wall, 0.125 in corrosion allowance, set on the shell with a single 0.3125 in inner fillet (Leg41).

UG-37 area replacement, P = 285 psi at 650 °F:

A_required	A_available	A₁	A_welds	Result
0.0928 in²	0.1781 in²	0.0804 in²	0.0977 in²	Adequately reinforced

UG-44 minimum nozzle neck: t_req = 0.285 in, t_min = 0.35 in. Passes.

UG-41 weld failure path:

Weld load W (lbf)	W1-1 (lbf)	Path 1-1 strength (lbf)	W2-2 (lbf)	Path 2-2 strength (lbf)
688.55	1,670.67	13,913.49	2,877.25	7,197.81

All paths are stronger than the applied weld loads.

UCS-66 toughness:

tr = (P x R) / (S x E – 0.6 x P) = (285 x 0.65) / (20,000 x 1 – 0.6 x 285) = 0.0093 in Stress ratio = (tr x E*) / (tn – c) = (0.0093 x 1) / (0.35 – 0.125) = 0.0415 Stress ratio ≤ 0.35, so MDMT per UCS-66(b)(3) = -155 °F.

The coupling is exempt from impact testing at the -20 °F design MDMT with a -155 °F rated MDMT at full pressure.

Other nozzles, summary

Nozzle	A_req / A_avail (in²)	UG-44 t_req / t_min (in)	UCS-66 stress ratio	Rated MDMT (°F)
N-H-01 (2″ 3M, head, set-through, double fillet)	0.179 / 0.349	0.214 / 0.218	0.0545	-155
N-S-01 (2″ 6M, shell, set-on, single fillet)	0.179 / 0.349	0.214 / 0.218	0.0276	-155
N-S-02 (1″ 6M, shell, passes Cat A joint)	0.117 / 0.218	0.114 / 0.179	0.0203	-155
N-S-03 (3/4″ 6M, shell, set-on, single fillet)	0.0928 / 0.1781	0.285 / 0.350	0.0415	-155

Source: registered calculation package 008_0285_0125_+650_-20_V_1 Rev. 1, pages 14 to 30. Personal identifiers, license numbers, and seal images have been removed from the public version. The original sealed PDF is held in the Reece quality records.

Why this case study is on the public site

Most of the small ASME pressure vessels Reece registers in Alberta and other Canadian provinces look like this one in scope: 50 to 200 lb empty, registered under a CRN, sealed by a Permit-to-Practice firm, and built from pipe-and-cap or pipe-and-cover construction. Buyers and design engineers shopping for that work want to see actual code calculations, not a brochure photograph. This page reproduces the registered calculation summary for one such vessel so an engineer can read it, an AI search assistant can cite it, and a procurement engineer can decide whether Reece is the right shop for a similar job.

If you have a pressure vessel, separator, or pressure-rated process equipment that needs to be designed, fabricated, and registered to ASME Section VIII Div. 1, Reece can take it from sketch to CRN under one roof.