knowledge

Technical specifications of pressure vessels

July 14, 2025
admin

Introduction

 Pressure vessels are   one of the most important industrial   equipment in the oil and gas, petrochemical, power and chemical industries. Due to their use in harsh operating conditions, these vessels require adherence to the strictest   technical specifications and design  standards. In this article, we will detail the technical specifications of pressure vessels according to international standards.

The main design criteria for pressure vessels

1. International Standards:

  • ASME  Section VIII: The Most Reliable Global Standard

  • EN 13445  : European Standard

  • PD 5500  : British Standard

  • 2000:  German Standard

2. Iranian National Standards:

  • ISIRI 7824  : National Standard for Pressure Vessels

  • Ministry of Petroleum  Regulations: for Oil and Gas Industries

Main design parameters

1. Main parameters:

  • Design  pressure: generally 10% higher than operating pressure.

  • Design  temperature: the highest expected temperature.

  • Volume  : in liters or cubic meters

  • Liquid density

  • Corrosion properties of liquids

2. Environmental standards:

  • Weather conditions

  • Seismic loads

  • Wind loads

  • Snow loads

Materials and materials used

1. Carbon steel:

  • SA-516 Gr.70  : Most Used Grade

  • SA-285 Gr.C  : For Low Pressures

  • SA-537  : For Low Temperatures

2. Alloy steel:

  • SA-387 Gr.11  : Corrosion Resistant

  • SA-240 Type 316  : Stainless Steel

3. Non-metallic materials:

  • Fiberglass  : for corrosive environments

  • Polyethylene  : for special applications

Main technical calculations

1. Calculation of wall thickness:

  • Basic  formula: t = (PR)/(SE-0.6P)

    • T: Thickness(mm)

    • P: Design pressure (MPa)

    • R: Inner diameter(mm)

    • S: permissible stress (MPa)

    • (E) Welding efficiency coefficient

2. Skull calculations:

  • Hemispherical skull: thinner

  • Oval cover (2:1):  the most common type

  • Flat  head: for low pressures

طرق فحص أوعية الضغط: دليل كامل لمراقبة الجودة والسلامة

Construction and welding considerations

1. Welding requirements:

  • Certified Welding Procedures (WPS)

  • Welding Qualification (WPQ)

  • Preheating and subsequent heating

2. Quality Control:

  • Radiological Test (RT)

  • Ultrasonic Test (UT)

  • Magnetic Particle (MT) Test

  • Fluid penetration (PT) test

Accessories & Connectors

1. Types of nozzles:

  • Inlet/outlet nozzle

  • Discharge nozzle

  • Nozzle for precision instruments

2. Safety valves:

  • Pressure Relief Valve (PSV)

  • Emergency Drain Valve

  • Pressure Control Valve

3. Measuring equipment:

  • Pressure gauge

  • Beer Harari Karbai

  • Level sensors 

Pressure vessel test

1. Hydrostatic pressure test:

  • Test  pressure: usually 1.3 to 1.5 times the design pressure

  • Duration  : At least 30 minutes

  • Conditions  : Room temperature water.

2. Pneumatic test:

  • For Special Occasions

  • Pressure less than hydrostatic test pressure

  • Strict security precautions

Protection and security systems

1. Emergency Systems:

  • Safety valves

  • Broken discs

  • Rapid evacuation systems

2. Corrosion protection:

  • Inner covers 

  • Sacrificing anodes

  • Cathode Systems

Identification and marking boards

Required information on the identification plate:

  1. Secret number

  2. Design pressure and temperature

  3. Tank Capacity

  4. Standard Code

  5. Date of manufacture

  6. Manufacturer ID

Periodic maintenance and inspection

1. Inspection Program:

  • Annual eye exam

  • Full inspection every 5 years

  • Non-destructive periodic tests

2. Required Documents:

  • Inspection Reports

  • Repair history

  • Test Certificates

Special considerations for different industries

1. Oil and gas industries:

  • Resistance to hydrogen sulfide

  • Adverse environmental conditions

  • Dynamic loads

2. Food and pharmaceutical industries:

  • Easy cleaning

  • FDA approved materials

  • Hygienic Design

Pressure vessel design program

1. Popular Software:

  • Elite PV

  • pressure

  • AutoPIPE ship

  • SolidWorks pressure vessel

2. Main features:

  • Stress calculations

  • Stability Analysis

  • Preparation of building plans

  • Cost Estimation

Conclusion

 The design and construction  of pressure vessels requires   in-depth technical knowledge and strict adherence   to standards. The selection of the right materials, accurate calculations, and total quality control are key to the construction of this vital equipment   .    

To ensure the long-term safety and performance of pressure vessels, regular checks and preventive maintenance are essential   . Cooperation with  experienced   engineers and internationally accredited companies   ensures the quality and safety of this equipment.