Introduction

This article provides comprehensive information about Pressure Vessels. Continue reading to learn about:

• What Pressure Vessels are
• Different types of Pressure Vessels
• Material selection for Pressure Vessels
• Pressure Vessel design
• Quality testing and inspection of Pressure Vessels
• And more...

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Chapter 1: Understanding Pressure Vessels

Pressure vessels are enclosed containers designed to hold liquids, gases, or vapors at pressures significantly different from ambient conditions. They serve critical functions across various industries including petrochemical, oil and gas, chemical processing, and food production. Common examples include reactors, flash drums, separators, and heat exchangers.

These vessels must comply with strict standards and regulations. The ASME Boiler and Pressure Vessel Code (BPVC) provides comprehensive guidelines for design, construction, testing, inspection, and certification. ASME BPVC Section VIII specifically addresses pressure vessels and divides into three parts:

• Division I applies to pressure vessels operating above 15 psig. It uses a design-by-rule approach based on normal stress theory.
• Division II covers vessels up to 10,000 psig with stricter requirements, employing design-by-analysis based on maximum distortion energy theory.
• Division III specifies requirements for vessels exceeding 10,000 psig.

The API 510 standard focuses on in-service inspection, rating, repair, and alteration of pressure vessels to maintain operational safety.

Pressure vessels must operate within defined safety limits for temperature and pressure. only certified professionals should handle operations, as leaks or failures pose significant environmental risks.

Plasite Lined Tank from Gladwin Tank Manufacturing

Chapter 2: Types of Pressure Vessels

Pressure vessels are specialized containers that safely store liquids, gases, or vapors under pressure. They're essential in industries like chemical processing, oil and gas, power generation, and food production. These vessels can be classified by function or geometry, each with specific applications and benefits. Understanding these types is crucial for proper equipment selection and regulatory compliance.

Classification by Function

• Storage Vessels: Designed for holding liquids, vapors, and gases under pressure, these are common in petrochemical plants and refineries. They store products like LPG and liquid nitrogen, with design considerations including MAWP and material compatibility.

  

• Heat Exchangers: These transfer thermal energy between fluids while maintaining pressure integrity. Used in power plants and pharmaceuticals, they must withstand thermal cycling and pressure stresses.

  

• Boilers: Pressurized vessels that generate steam for power and heating. Designs include water-tube and fire-tube boilers, constructed from high-strength alloys to handle thermal stresses.

  

• Process Vessels: Used for chemical or physical transformations, including:

  • Distillation columns for separating mixtures by volatility, including flash and fractional distillation types.

    

  • Decanters for phase separation

  • Industrial mixers for homogenizing substances under pressure.

    

  • Chemical reactors for controlled reactions

• Common reactor types include:

  • Jacketed reactors with temperature control systems.

    

  • Packed bed reactors with fixed catalysts
  • Fluidized bed reactors for enhanced heat transfer

Classification by Geometry

• Spherical Vessels: Ideal for high-pressure gas storage due to uniform stress distribution. Common in LNG and ammonia storage.

  

• Cylindrical Vessels: The most common design, featuring various head types:

  • Hemispherical heads for high-pressure applications

    

  • Torispherical heads for moderate pressure

    

  • Ellipsoidal heads offering strength and efficiency

    

  

Vessel Orientation

Cylindrical vessels can be installed vertically or horizontally based on application needs:

• Vertical orientation is preferred for:
  • Space-constrained facilities
  • Processes requiring small footprints
  • Improved mixing efficiency
  • Enhanced separation processes