## ASME PRESSURE VESSEL

The purpose of this presentation is to provide a background and understanding of the ASME Code for Pressure Vessel Design for the Chemical and Process Industry as applicable in the United States and most of North and South America.

## ASME Section I and Section VIII Fundamentals - Part 3

## ASME SECTION VIII - Division 1, Division 2, Division 3:

ASME Section VIII, Rules for Ignition and Non-Ignition Pressure Vessels, is divided into three areas that apply to design, manufacture, inspection, testing, and certification. The formulas and allowable stresses shown on this drawing apply only to Division 1, the main code. Contains mandatory and non-mandatory appendices detailing supplemental design criteria, non-destructive testing and inspection acceptance standards.

Also included is the use of seals with the U, UM and UV code symbols.

## 4.1 - SECTION VIII - Thin cylindrical shells:

ASME Section VIII, Division 1, Paragraph UG-27 formulas used to calculate wall thickness and design pressure of pressure vessels are: a) Circumferential stress (longitudinal welds):

With P < 0.385 SE:

### Example 5: thin cylindrical shells:

A vertical boiler is constructed using SA-515-60 in accordance with Section VIII-1. It has an inside diameter of 96 inches and an inside pressure of 1000 psi at 450°F. The corrosion allowance is 0.125 inches and the joint efficiency E = 0.85. Calculate the required shell thickness. (Consider SA-515-60 = 15,000 psi allowable stress, ASME Section II, Table 1A, Div.1).

Since P < 0.385 SE = P < 6545 psi. Since 1000 psi < 6545 psi, therefore, use Equation 1.3:

t = PR… + C/SE – 0,6P

Assuming inside radius = (48 inches) and corrosion allowance = 0.125 inches.

t = 1000 x 48 …………. + 0,125 / 2(15.000)(0,85) – 0,6(1.000)

t = 2.052 inches

### SECTION VIII - Thick cylindrical shells:

For internal pressures greater than 3000 psi, special considerations apply as noted in paragraph U-1(d). As the t/R ratio increases above 0.5, an accurate equation is needed to determine thickness. The formulas in ASME Appendix 1, Supplementary Design Formulas Used for Calculating Thick Walls and Design Stress are:

**a) For longitudinal seams:**

With P > 0.385 SE:

**b) For circumferential welds:**

With P > 1.25 SE:

Where: R = construction radius (in):

Z = dimensionless factor.

### Example 6: thick cylindrical shells:

a) Se P > 0,385SE:

Calculate the required case thickness of an accumulator with a design pressure of P = 10,000 psi, R = 18 inches, S = 20,000 psi, and E = 1.0. Allow 0.125 inch corrosion tolerance.

Since P > 0.385 SE = P > 7700 psi. Therefore, since 10,000 psi > 7,700 psi, use equation 1.7:

t = R (Z ½ - 1) =

Z = (20 000).(1,0) + 10 000 / (20 000).(1,0) – 10 000 = 30 000/10 000 = 3

t = (18) (3½ – 1) + 0.125 = 8.08 pulg.

### Example 7: thick cylindrical shells:

b) With P < 0.385 SE:

Calculate the required lining thickness for an accumulator with a design pressure of P = 7650 psi, R = 18 inches, S = 20,000 psi, and E = 1.0. Assume corrosion tolerance = 0.

As P < 0.385 SE = P < 7700 psi. Since 7650 psi < 7700 psi, therefore, use Equation 1.3:

t = PR… + C/SE – 0,6P =

t = 7,650 x 18………… + 0 / (20,000)(1,0) – 0,6(7,650)

t = 8.9 inches

### Example 8 - Comparison between Equation 1.3 and Equation 1.7:

Calculate shell thickness by comparing Equation 1.3 with another answer using Equation 1.7.

t = R (Z ½ - 1) =

Z = (20 000)(1,0) + 7650 = 27 650 / (20 000)(1,0) - 7650 = 27 650 / 12 350 = 2,24

t = (18 + 0) (2.24 ½ - 1) = 8.9 pulg.

## ASME I and ASME-ANSI B31 - Pressure lines - Minimum wall thickness:

Per ASME Section I and ANSI B31, the minimum gauge of pressure pipe is:

t (min)= minimum required wall thickness (inches);

P = design pressure (psig);

D = outer tube diameter (inches);

S = allowable stress in the pipeline (psi);

E = longitudinal connection factor - E = 1.0 for unwelded pipe, E = 0.85 for ERW pipe;

C = corrosion allowance, typically 0.05 inch.

y = ASME wall thickness coefficient according to Table 304.1.1 for ferritic steels, where:

y = 0.4 for T <= 900°F;

y = 0.5 for 900 < T <= 950°F;

y = 0.7 for 950 < T <= 1000ºF

## ASME SECTION VIII - Reinforcement wall plate:

The standard construction method uses a heavier wall plate at the equator of the boat to take the extra stresses caused by the legs being joined together. The formula for calculating the wall thickness of a segmented plate to be welded to a spherical container or shell is:

t = PL…… + C / 2SE – 0,2P

L = March/2

From where:

t = minimum building wall thickness (in.);

P = design pressure (psi); Di = internal diameter of the sphere (in);

L = sphere radius (inches);

E = pipe weld factor (1.0 for seamless pipe; 0.85 = for welded pipe);

C = corrosion tolerance (0 for no corrosion; 0.0625 in general use; 0.125 maximum);

S = Maximum allowable voltage per ASME Section II, Table 1A.

## ASME SECTION I: Concave head formula:

Cup heads can be made by a combination of processes, turning and grinding, with the spherical radius being made by the spinning process and the joint being created by the grinding process. Flanged and domed heads can be formed in a size range from 4 to 300 in diameter and in a thickness range from 14 gauge to 1-1/2 inch thick. Pressure vessel covers and flared ends are essentially the same thing: the covers of a pressure vessel or industrial boiler tank, designed with a flanged edge to make it easier to weld the head to the main body of the tank.

## Bare concave heads, unsupported:

Clause PG-29.1 specifies that the thickness of a concave head in the raw, undeformed state, with pressure on the concave side, if it is a segment of a sphere, shall be calculated using the following formula:

From where:

t = minimum head thickness (in);

P = maximum allowable working pressure (psi);

L = radius of concave side (inches);

S = maximum allowable working voltage (psi).

Paragraph PG-29.2 states: “The radius to which the head projects shall not be greater than the outer diameter of the flange portion of the head. If two radii are used, the larger one is included in the formula as the value of L.”

### Example 9 - segment of a concave spherical head:

Calculate the thickness of a seamless, bare, strapless concave head by applying pressure on the concave side. The head has a 42.7" bore with a 36.0" crown radius. The maximum allowable working pressure (MAWP) is 360psi and the material is SA-285A. Temperature does not exceed 480°F. Indicate whether this thickness corresponds to the code. (Solution: Use equation 1.11.)

P = 360 psi;

L=36.0 inch;

S = 11,300 psi – SA-285 A and 480°F.

t = 5 (360 x 36) / 4,8 (11.300)

t = 1.19 pulg.

PG-29.6 states: "No head, except a hemispherical head, shall be less thick than required for seamless pipe of the same diameter." Therefore, the minimum tube thickness is:

t =360 x 42,7 / 2(11.300)(1,0) + 2 (0,4)(360)

t = 0.67 inches. The calculated head thickness meets standard requirements like 1.19 > 0.67.

### Example 10 - Segment of a concave spherical head with flanged shaft:

Find the thickness of a seamless concave head with no gusset with pressure on the concave side and a 6.0" x 16" flanged manhole. The head diameter is 47.5 inches with a bowl radius of 45 inches. is SA-285-C and the temperature does not exceed 428°F.

The first thing to check is, is the bowl radius at least 80% of the bowl diameter?

Plato's Radius = 45 = 0.947 > 0.8

Case diameter = 47.5

The radius of the bowl meets the criteria, use equation 1.11:

This thickness is for an empty head. ASME - PG-29.3 requires that this thickness be increased by 15% or 0.125 inch, whichever is greater. Since 0.764 × 0.15 = 0.114 inches, which is less than 0.125 inches, the thickness needs to be increased by 0.125 inches.

Therefore, the required head thickness is t = 0.764 + 0.125 = ~0.90 inches.

## Complete or seamless hemispherical head:

The thickness of a blank full hemispherical head without shoulders with the pressure on the concave side is calculated using the following formula:

t = minimum head thickness (in)

P = maximum allowable working pressure (psi)

L = radius where the head was formed (in)

S = maximum allowable operating voltage (psi)

Note: The above formula is not used when the required head thickness, as specified by the formula, exceeds 35.6% of the inside radius. Instead, use the following formula:

### Example 11 - Hemispherical or seamless head:

Calculate the minimum thickness required for a complete, tension-free, hemispherical head block. The radius to which the head is concave is 7.5 inches. The MAWP is 900 psi and the head material is SA 285-C. The average head temperature is 570°F.

Solution: Use equation 1.13.

P = 900 psi;

L=7.5 inches;

S = 13.800 psi - (a 285°C e 600°F).

t = 900 x 7,5 / 2 (13.800) - 0,2 (900) = 0,24plg.

Make sure this thickness exceeds 35.6% of the inside radius = 7.5 x 0.356 = 2.67 inches. It does not exceed 35.6%, so the calculated head thickness meets the requirements of regulations.

## ASME SECTION VIII - DIVISION 1: Flat head formula:

Domed and domed heads can be formed from carbon steel, stainless steel and other ferrous and non-ferrous metals and alloys. Flanged and domed heads can be formed in a size range from 4" to 300" in diameter and in a thickness range from 1/8" to 1½" thick. ASME Section VIII – Division 1 sets out the rules for vaulted floors. The most common configurations are spherical, hemispherical, elliptical (or ellipsoidal), and torispherical shapes.

## Concave head shapes:

The appearance of shapes is a source of confusion for beginners and even ASME Section VIII experts. To shed some light on these topics, see the curriculum below:

In the next issue, we will discuss ASME Section VIII heading formulas.

Quelle: ASME International Boiler and Pressure Vessel Code

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## FAQs

### What is ASME Section VIII Division 3? ›

ASME B&PV Code, Section VIII, Division 3 contains mandatory requirements, specific prohibitions, and non-mandatory guidance for the design, materials, fabrication, examination, inspection, testing, and certification of high pressure vessels and their associated pressure relief devices.

**What is the difference between ASME Section VIII and Section I? ›**

ASME Section VIII is the section of the ASME Boiler & Pressure Vessel Code (BPVC) that covers pressure vessels. It specifically refers to the pressure vessels that operate at pressures, either internal or external, that exceed 15 psig. ASME Section I covers steam applications on fired vessels (boilers).

**How do you calculate maximum allowable stress in ASME? ›**

**At 250 degrees S = min(0.9*0.85*139 or 0.85*502/3.5) = 106.34 MPa**, which is very close to the listed allowable of 107 MPa. At 375 degrees S = min(0.9*0.85*125 or 0.85*495/3.5) = 95.63 MPa, which is very close to the listed allowable of 95.7 MPa.

**What is Section VIII Division 1 of the ASME Code? ›**

This Division of Section VIII provides requirements applicable to the design, fabrication, inspection, testing, and certification of pressure vessels operating at either internal or external pressures exceeding 15 psig. Such pressure vessels may be fired or unfired.

**What is the difference between ASME Section 8 Division 1 and 2 and 3? ›**

ASME Section VIII in itself consists of three divisions, where **Division 1 is concentrated on a design-by-rule approach and Division 2 on the design-by-analysis approach**. Division 3 is supposed for designing pressure vessels that need internal or external operating at a pressure above 10,000 PSI.

**What is ASME Section VIII summary? ›**

ASME Section VIII of the code is dedicated to pressure vessels. It gives detailed requirements for the design, fabrication, testing, inspection, and certification of both fired and unfired pressure vessels.

**What is the difference between ASME VIII Division 1 and 2? ›**

ASME Section VIII, Division 2 is intended for purpose-specific vessels with a defined fixed location. Another major difference between the Division 1 and Division 2 lies in failure theory. **While Division 1 is based on normal stress theory, Division 2 is based on maximum distortion energy (Von Mises)**.

**What ASME Code Section 1 is about? ›**

This Section provides requirements for all methods of construction of power, electric, and miniature boilers; high temperature water boilers, heat recovery steam generators, and certain fired pressure vessels to be used in stationary service; and power boilers used in locomotive, portable, and traction service.

**What is the pressure limit for ASME Section VIII Div 1? ›**

Pressure ranges in ASME Sec VIII code: Pressure range starts from **15 PSI to 3000 PSI** can be designed as per ASME Sec VIII Division 1. Pressure range starts from 3000 PSI to 10,000 PSI can be designed as per ASME Sec VIII Division 2.

**How do you calculate maximum allowable working pressure? ›**

**MAWP Calculations - Calculate MAWP per locations with variou standard formulas.**

- MAWP summary for a location.
- Cylindrical shells Inside Radius P=SEt/R+0.6t.
- Cylindrical shells Inside Radius Division 2 P=SEln((t/R)+1)
- Cylindrical shells Outside Radius P=SEt/R-0.4t.

### How do you calculate maximum and minimum stress? ›

**Page 1**

- Principle Stresses and Maximum In-Plane Shear Stress.
- To determine the maximum and minimum normal stress we must differentiate σx ' with respect to θ and equate to zero.
- σx' = (σx + σy ) + (σx-σy) cos 2 θ + τxy. ...
- dσx' ...
- tan 2θp = τxy.

**How do you calculate allowable stress for piping? ›**

The standard equation for hoop stress is **H = PD _{m} /2t**. In this equation, H is allowable or hoop stress, the P is the pressure, t is the thickness of the pipe, and D is the diameter of the pipe.

**What is ASME Code Section VIII Div 1 Appendix 8? ›**

The ASME Code Section VIII Div. 1 Mandatory Appendix 8 **covers the acceptance criteria for Penetrant testing on the weld**. Please note API codes for rotating equipment also refer to this code.

**What is the minimum thickness for ASME VIII Div 1? ›**

ASME BPV Code Section VIII D. 1 states that wall thickness should always be at least **1/16 in**, not considering corrosion allowance, material, or dimensions.

**Is ASME a code or standard? ›**

ASME is the leading international developer of **codes and standards**, hereafter referred to as standards, associated with the art, science, and practice of mechanical engineering. ASME is the globally recognized, trusted source of consensus standards since 1884.

**What does ASME Section Meaning? ›**

**The American Society Of Mechanical Engineers**.

**What is the difference between ASTM and ASME standards? ›**

Basically ASTM creates the material specifications and standard test methods to determine compliance. ASME selects those ASTM materials which will perform adequately in boiler or pressure vessel service and accepts them with stated limitations.

**What are ASME VIII Division 2 requirements? ›**

**Requirements for an ASME Section VIII, Division 2 UDS – Part 1 of...**

- A) Installation Site. ...
- B) Vessel Identification. ...
- C) Vessel configuration and controlling dimensions. ...
- D) Design Conditions. ...
- E) Operating Conditions. ...
- F) Design Fatigue Life. ...
- G) Materials of Construction. ...
- H) Loads and Load Cases.

**Why is ASME code important? ›**

ASME code doesn't just indicate the accuracy, performance and efficiency of pressure vessels, it also **ensures that during production of pressure vessels in industries, high level of caution and safety is followed to protect the workers from any kind of dangerous situation**.

**What does ASME stand for all five words? ›**

**American Society of Mechanical Engineers** (ASME)

### What is the latest edition of ASME Section VIII? ›

Revision: 2023 Edition, **July 1, 2023**.

**What is flange leakage ASME Section VIII? ›**

ASME Sec VIII flange leakage method is **performed when the flange analysis using the pressure equivalent method shows failure in Caesar II**. The pressure equivalent method is believed to be highly conservative and does not provide the actual results.

**How many ASME standards are there? ›**

ASME – American Society of Mechanical Engineers

It is an International Boiler and Pressure Vessel Code is made of **12 sections** and contains over 15 divisions and subsections.

**What is P number and group number in ASME? ›**

A P-Number is **an alphanumeric designation assigned to a group of materials**. These materials are grouped based on their similar weldability and mechanical characteristics. P-Numbers are assigned to base metals to reduce the number of welding and brazing procedure qualifications required to perform work.

**What is latest ASME code? ›**

The **2021 ASME BPVC** officially is the latest edition and is required for ASME Stamp Certification.

**What is the current ASME standard? ›**

**5** is a standard published by the American Society of Mechanical Engineers (ASME) to establish rules, symbols, definitions, requirements, defaults, and recommended practices for stating and interpreting Geometric Dimensions and Tolerances (GD&T).

**What are the different ASME codes? ›**

**ASME Piping Codes & Valve Standards**

- ASME B16. 34 Valves Flanged, Threaded and Welding End.
- 1 Power Piping.
- 3 Process Piping.
- 4 Pipeline Transportation Systems for Liquids and Slurries.
- 8 Gas Transmission and Distribution Piping Systems.

**What is maximum allowable stress value? ›**

Thus, the maximum allowable stress value for a 60,000-psi tensile strength material will become **20,000 psi**. Many companies require that all their pressure vessels be constructed in accordance with Division 2 because of the more exacting standards.

**What is the maximum allowable accumulation of pressure? ›**

The allowable accumulation for pressure vessels protected by a single relief device is **110%**, as shown in Figure 1. The exception to this is fire exposure scenarios, for which the allowable accumulation is 121% of the MAWP. When multiple relief devices are used for non-fire scenarios, the allowable accumulation is 116%.

**What is maximum allowable working pressure in pump? ›**

Maximum allowable working pressure (MAWP) is **an American Society of Mechanical Engineers (ASME) designation that establishes the rating for pressure-relief components on vessels**. It measures the greatest amount of pressure that the weakest part of the vessel can handle at specific operating temperatures.

### How do you find the maximum and minimum volume? ›

To find the maximum possible volume, **add the greatest possible error to each measurement, then multiply**. To find the minimum possible volume, subtract the greatest possible error from each measurement, then multiply.

**How do you determine the minimum or maximum value? ›**

We'll determine whether it is a maximum or minimum value **by looking at the a value or checking the sign of the second derivative**. A positive value means the parabola opens up, so it has a minimum value. A negative value means the parabola opens down, so it has a maximum value.

**How do you find the minimum and maximum measurements? ›**

key idea. To find the minimum possible volume, **subtract the greatest possible error from each measurement before calculating**. To find the maximum possible volume, add the greatest possible error to each measurement before calculating.

**What is the allowable pressure rating for ASME B31 3? ›**

Therefore, the Victaulic established **500psi (34.5 Bar)** maximum recommended pressure rating is within the design requirements of ASME B31. 3. (Note: The stress level at 300°F was chosen as it is the upper limit of the VicPress for Schedule 10S highest temperature seal material.)

**What is the maximum allowable stress for ASME B31 3? ›**

Hence the value of allowable stress is **20ksi from minimum temperature to 400°F**.

**What is allowable stress in ASME B31 3? ›**

For B31. 3 Process piping, allowable stress is **tensile strength at temperature divided by 3**. Note! for B31. 1 - Power piping, allowable stress is tensile strength at temperature divided with 3.5.

**How to read ASME? ›**

ASME = **American Society for Mechanical Engineers**. ASTM= ASTM International erstwhile American Society for Testing and Materials.

**What is minimum allowable thickness? ›**

**For design thicknesses 1 inch (25 mm) or greater, the minimum allowable individual thickness shall be the design thickness minus 1/4 inch (6.4 mm)**. For design thicknesses less than 1 inch (25 mm), the minimum allowable individual thickness shall be the design thickness minus 25 percent.

**What is the minimum required wall thickness? ›**

Minimum thickness **h**

**4 in.** **7.5 in**. Only applies to walls designed in accordance with the simplified design method of 11.5.

**What is the minimum wall thickness required by the code? ›**

The minimum thickness of exterior walls in one-story buildings shall be **10 inches (254 mm)**. The walls shall be laterally supported at intervals not exceeding 24 feet (7315 mm). The minimum thickness of interior load-bearing walls shall be 8 inches (203 mm).

### What are the most important ASME standards? ›

In particular, the **ASME Section 8 (Boiler and Pressure Vessel Code)** is one of the most important and is even used in countries all around the world.

**Is ASME certification required? ›**

When is ASME certification required? **ASME certification is useful when your product needs to comply with local laws or codes**. The ASME Certification Mark provides a way of complying with the laws and regulations in nearly all U.S. States and Canadian Provinces.

**What is the difference between a code and a standard? ›**

A code is a model, a set of rules that knowledgeable people recommend for others to follow. It is not a law, but can be adopted into law. A standard tends be a more detailed elaboration, the nuts and bolts of meeting a code.

**What is the difference between ASME VIII Div 1 and Div 2? ›**

ASME Section VIII, Division 2 is intended for purpose-specific vessels with a defined fixed location. Another major difference between the Division 1 and Division 2 lies in failure theory. **While Division 1 is based on normal stress theory, Division 2 is based on maximum distortion energy (Von Mises)**.

**What is Article kd 10 of ASME BPVC Section VIII Division 3? ›**

Article KD-10: **For all vessels in gaseous hydrogen transport and storage service**. Each pressure component shall be evaluated for the specified fatigue cycle and shall meet the fracture toughness requirements in this article. These requirements are in addition to other requirements in Division 3.

**What is the difference between working pressure and design pressure? ›**

1. MAWP or maximum allowable working pressure is the maximum pressure at a specific temperature at which a vessel can function correctly. In contrast, design pressure is the stress imposed on an equipment's internal and external pressure that the equipment seems to sustain.

**How do you calculate design pressure? ›**

Design pressure= **Pump shut off head +normal operating pressure of suction vessel+ head between the tangential line of the suction vessel and the centerline of the pump impeller**. Pump shut-off head can be calculated as Maximum suction pressure + 1.25 x Normal differential pressure.

**What is the difference between pressure vessel and storage tank? ›**

Pressure vessels store gases or liquids at a pressure above atmospheric pressure. Their Maximum Allowable Operating Pressure (MAOP) starts at 15 PSI but can reach up to 150,000 PSI. On the other hand, storage tanks have an MAOP of 15 PSI and only hold gases or liquids at atmospheric pressure.

**Are ASME standards mandatory? ›**

ASME cannot force any manufacturer, inspector, or installer to follow ASME standards. Their use is voluntary. **Standards become mandatory when they have been incorporated into a business contract or incorporated into regulations**.

**What is Section VIII Division 2 of the ASME Code? ›**

This Division of Section VIII provides requirements applicable to the design, fabrication, inspection, testing, and certification of pressure vessels operating at either internal or external pressures exceeding 15 psig. Such vessels may be fired or unfired.

### What is the ASME Code and why is it important to the pressure vessel design? ›

What is the ASME pressure vessel inspection code? A leading standard for pressure equipment and components worldwide, the ASME Boiler and Pressure Vessel Code (ASME Code) **provides requirements for manufacturer certification and quality assurance**.

**What does ASME Section 3 cover? ›**

Section III of the ASME Code Address **the rules for construction of nuclear facility components and supports**.