ASME Boiler and Pressure vessel code (BPVC) Section VIII Division 1 is focused on a design-by-rule approach and Division 2 on design-by-analysis approach. While ASME Section VIII, Division 1's design-by-rule approach is most commonly utilized by engineers to size the pressure vessel according to the application requirements, it is quite a conservative approach. The empirical relations and other mandatory and non-mandatory design criteria often result in an expensive pressure vessel design. ASME Section VIII, Division 2's design-by-analysis approach requires more detailed calculations than Division 1. Although this may increase the cost of pressure vessel design, it allows pressure vessels to withstand higher stresses. Based on size and design parameters imposed, choice will be determined. This paper emphasis on Pressure vessel design by analysis versus design by rule

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International Journal of Research in Engineering, Science and Management

Volume-2, Issue-6, June-2019

www.ijresm.com | ISSN (Online): 2581-5792

Abstract: ASME Boiler and Pressure vessel code (BPVC)

Section VIII Division 1 is focused on a design-by-rule approach

and Division 2 on design-by-analysis approach. While ASME

Section VIII, Division 1's design-by -rule approach is most

commonly utilized by engineers to size the pressure vessel

according to the application requirements, it is quite a

conservative approach. The empirical relations and other

mandatory and non-mandatory design criteria often result in an

expensive pressure vessel design. ASME Section VIII, Division 2's

design-by -analysis approach requires more detailed calculations

than Division 1. Although this may increase the cost of pressure

vessel design, it allows pressure vessels to withstand higher

stresses. Based on size and design parameters imposed, choice will

be determined. This paper emphasis on Pressure vessel design by

analysis versus design by rule

Keywords: ASME, BPVC, Design.

1. Introduction

Pressure vessels are an integral part of many manufacturing

facilities and processing plants, enabling the safe storage of

pressurized liquids and gases. From industrial boilers to

gasoline tankers, pressure vessels operate in a wide array of

potentially hazardous environments. However, if not properly

designed, constructed and maintained, pressure vessels can be

extremely dangerous. ASME Boiler and Pressure vessel code

Section VIII in itself consists of 3 divisions, where Division 1

is focused on a design-by-rule approach and Division 2 on

design-by -analysis approach. Division 3 is meant for designing

pressure vessels that require internal or external operating at a

pressure above 10,000 PSI.

2. History of design code

Most pressure vessels employed in industries today are

designed according to the ASME BPVC Section VIII, which

consists of standard codes and rules that a manufacturer is

required to follow. More than 60 nations generally recognize

and apply the BPVC for pressure vessel design. BPVC Section

VIII is specifically meant to guide mechanical engineers in

designing, constructing and maintaining PVs operating at either

internal or external pressure exceeding 15 PSIG. While ASME

Section VIII, Division 1's design-by -rule approach is most

commonly utilized by engineers to size the pressure vessel

according to the application requirements, it is quite a

conservative approach. The empirical relations and other

mandatory and non-mandatory design criteria often result in an

expensive pressure vessel design. 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).

The codes mentioned under Section VIII for both divisions

also include appendices. These appendices are alternative or

supplementary rules that serve as guidelines, since they are less

frequently employed than the main body codes. However, the

appendices themselves contain both mandatory and non-

mandatory sections.

3. Pressure vessel construction code requirement

Although it is possible to construct a pressure vessel of any

shape and size, sections of cylinder, sphere and cone are usually

preferred. A more common pressure vessel design consists of a

cylinder closed with end caps, known as heads, that are usually

hemispherical. Spherical pressure vessel design is typically

stronger than a cylindrical shape with the same wall thickness.

However, spherical pressure vessels are difficult and costly to

manufacture, which makes cylindrical shape pressure vessels

with semi-elliptical heads preferred in many cases.

Typically, pressure vessels are made of steel, but there are

some that employ composite materials, such as carbon fiber,

ceramics and polymers. Modern pressure vessels include safety

features such as relief valves to relieve excessive pressure from

the container and ensure safe operation. And most pressure

vessels today are designed with a leak-before-burst feature,

which enables the vessel to relieve pressure by leaking the

contained fluid, rather than by means of an immediate and

potentially explosive fracture. In cases where leak before burst

design is not possible, pressure vessels are required to be

designed with more stringent requirements for fatigue and

fracture failure modes.

Overview of Pressure Vessel Design using

ASME Boiler and Pressure Vessel Code

Section VIII Division-1 and Division-2

N. V. Raghavaiah

Mechanical Engineer, Mechanical Section, HWPM, Aswapuram, India

International Journal of Research in Engineering, Science and Management

Volume-2, Issue-6, June-2019

www.ijresm.com | ISSN (Online): 2581-5792

A. Division 1

Pressure typically up to 3000 psig.

Not much restrictions on materials; Impact Test

required unless exempted.

Design Factor 3.5 on tensile (4 used previously) and

other yield and temperature considerations.

NDE requirements may be exempted through

increased design factor.

Professional Engineer Stamp is usually not required.

Hydrostatic Test of 1.3 design pressure (1.5 was used

before 1999 Addenda)

U Stamp

B. Division 2

Pressure usually 600 psig and larger.

More restrictions on materials; Impact Test required.

Design Factor of 3 on tensile (lower factor under

reviewed) and other yield and temperature

considerations.

More stringent NDE requirements.

Professional Engineer Stamp is a must.

Hydrostatic Test of 1.25 design pressure

U2 Stamp

4. Design data requirement

A design engineer usually requires the following basic data

to size a pressure vessel:

Vessel function

Process materials and services (corrosion, deposits,

etc.)

Operating conditions (temperature and pressure)

Materials of construction

Dimensions and orientation

Type of vessel heads to be used

Openings and connections required

Heating/cooling requirements

Agitation requirements

Specification of internal fittings

Once the preliminary data is obtained, the pressure vessel

design can be initiated following the standard procedures

outlines in BPVC Section VIII. This section is further

subdivided into subsections and appendices, guiding the

engineer to determine general design requirements, fabrication

requirements and material requirements to effectively size the

pressure vessel.

5. Conclusion

Now it is understood that one of the main differences

between Divisions 1 and 2 is that Division 2 uses lower design

margins often resulting in higher material allowable stresses.

Design margins are reduction factors applied to the material's

ultimate tensile strength (UTS) for the purpose of setting

material allowable stresses in ASME II-D. The design margins

are currently 3.5 for Division 1, 3.0 for Division 2, Class 1 and

2.4 for Division 2, Class 2. In Division 1, hydrotest stresses are

not specifically limited and partial penetration nozzle welds are

permitted. In Division 2, hydrotest stresses are limited so

hydrotest stress calculations are mandatory and full penetration

nozzle welds are required.

Another major difference is the theory of failure assumed and

therefore the design equations used. Specifically, Division 1

uses the maximum principle stress theory while, starting with

the 2007 Edition, Division 2 uses Von Mises. As a result,

Division 1 uses two sets of design equations one for "thin" and

another for "thick" vessels while Division 2 uses one set of

equations for all vessel thicknesses. Of particular note are the

more accurate nozzle design and allowable compressive stress

(external pressure) rules in Division 2 both of which can

provide additional savings.

In general, thinner Division 2 vessels retain safety factors

that are comparable to thicker Division 1 vessels by

incorporating more extensive engineering analysis and design

requirements.

References

[1] AS ME BPVC section VIII Division-1, 2007 edition

[2] AS ME BPVC section VIII Division-2, 2007 edition

[3] Dennis R. Moss and M. Michael, " Pressure Vessel Design Manual. "

[4] ASNT– Over view on NDT

[5] ASME BPVC section V for NDT, 2007 edition.

... Pada ASME VIII divisi II diterapkan standar-standar yang lebih tinggi sehingga dapat diaplikaskan pada kondisi tekanan yang lebih besar. Untuk mendesain suatu pressure vessel dibutuhkan beberapa data seperti fungsi vessel, kondisi operasi (suhu dan tekanan), bahan konstruksi, dimensi dan orientasi, jenis head yang akan digunakan, persyaratan pemanasan/pendinginan, persyaratan agitasi, dan spesifikasi perlengkapan internal (Raghavaiah 2020 Namun ada beberapa masalah yang tidak dapat diselesaikan secara spesifik oleh kode dan standar, khususnya keterbatasan ukuran bahan baku pelat di pasaran. Umumnya pelat dijual dengan lebar sebesar 1,6 m. ...

  • Khairmen Suardi
  • Faris Fadli

AbstrakHead pada pressure vessel yang berbentuk melengkung, seperti: hemispherical, torispherical, dan ellipsoidal dapat dibuat dari pelat dengan lebar 2.5 m yang mengalami proses metal forming. Namun, pelat yang tersedia di pasaran pada umumnya memiliki lebar 1,6 m. Kondisi ini menjadi batasan apabila ingin menggunakan satu material pelat secara integral sehingga dibutuhkan pelat untuk membuat head dengan lebar yang lebih besar. Oleh karena itu, untuk membuat head dengan lebar 2,5 m dilakukan proses cold forming pada dua pelat yang dilas. Namun setelah proses dilakukan, terjadi kegagalan berupa timbulnya retakan di sekitar area las. Pada paper ini akan dibahas analisis kegagalan proses cold forming yang terjadi pada dua pelat ASME SA516 grade 70N yang digunakan sebagai base metal. Untuk menganalisis penyebab kegagalan, maka dilakukan pengujian kekerasan, tarik, metalografi, dan komposisi kimia. Selain itu juga dilakukan perhitungan untuk mengetahui nilai crack consists of hot (UCS), cold cracking (Pcm), dan carbon equivalent (CE). Hasil perhitungan menunjukkan bahwa material tersebut memiliki nilai UCS di bawah 30, nilai Pcm berada di antara 0,23-0,35%, serta berada di zona II pada diagram Graville dimana nilai tersebut menunjukkan bahwa material memiliki kemampulasan yang baik. Sementara dari hasil pengujian mekanis didapatkan nilai kekerasan dan kekuatan tarik yang lebih besar dari standar, yaitu masing-masing sebesar 300 HBW dan 621 Mpa dengan nilai elongasi yang masih tinggi, yaitu sebesar 21,8%. Hasil pengamatan metalografi menunjukkan terbentuk fase martensit namun dalam jumlah yang sedikit pada area heat affected zone (HAZ) dengan bentuk butir seperti jarum. Fase martensit ini berperan sebagai stress concentration yang menjadi titik awal retak ketika proses cold forming dilakukan. Terbentuknya fasa martensit ini disebabkan oleh proses preheat yang tidak sesuai serta heat input yang terlalu besar. Abstract The head on a pressure vessel with curved shapes such as hemispherical, torispherical, and ellipsoidal is derived from the formed plate. Generally the plates available in the market have a width of 1.6 m, this condition becomes a limitation if you want to use one plate material integrally so that a plate is needed to make a head with a larger width. Therefore, to make a head with a width of 2.5 m, a cold forming process is carried out on two welded plates. However, after the process is carried out, failure occurs in the form of cracks around the weld area. In this paper, we will discuss the failure analysis of the cold forming process that occurred on two ASME SA516 grade 70N plates used as base metal. In order to analyze the causes of failure, hardness, tensile, metallographic, and chemical composition tests were carried out. In addition, calculations were also carried out to determine the value of crack consists of hot (UCS), cold cracking (Pcm), and carbon equivalent (CE). From the calculation results it is evident that the material has a UCS value below 30, the PCm value is between 0.23-0.35%, and is in zone II on the Graville diagram where this value indicates that the material has good weldability. Meanwhile, from the results of mechanical testing, the hardness and tensile strength values are greater than the standard, which are 300 HBW and 621 Mpa, respectively, with a high elongation value, which is 21.8%. The results of metallographic observations showed that the martensite phase was formed but in small amounts in the heat affected zone (HAZ) area with needle-like grain shapes. This martensite phase acts as a stress concentration which is the starting point for cracks when the cold forming process is carried out. The formation of the martensite phase is caused by an inappropriate preheat process and the heat input is too large.

  • D.R. Moss
  • M.M. Basic

Pressure vessels are closed containers designed to hold gases or liquids at a pressure substantially different from the ambient pressure. They have a variety of applications in industry, including in oil refineries, nuclear reactors, vehicle airbrake reservoirs, and more. The pressure differential with such vessels is dangerous and due to the risk of accident and fatality around their use, the design, manufacture, operation and inspection of pressure vessels is regulated by engineering authorities, guided by legal codes and standards. Pressure Vessel Design Manual is a solutions-focused guide to the many problems and technical challenges involved in the design of pressure vessels to match stringent standards and codes. It brings together otherwise scattered information and explanation into one easy-to-use resource to minimize research and take readers from problem to solution in the most direct manner possible. Covers almost all problems that a working pressure vessel designer can expect to face, with 50+ step-by-step design procedures including a wealth of equations, explanations and data Internationally recognized, widely referenced and trusted, with 20+ years of use in over 30 countries making it an accepted industry standard guide Now revised with up-to-date ASME, ASCE and API regulatory code information, and dual unit coverage for increased ease of international use.