Fundamentals of Pressure Vessels and Selection Guide

Pressure vessels, as indispensable equipment in industrial production, are widely used in fields such as chemical engineering, energy, and pharmaceuticals. As an enterprise with rich experience in industrial equipment, Sinton Company has always been committed to providing customers with safe and reliable pressure vessel solutions. This article will systematically introduce the basic knowledge, classification, structure, selection key points, and accident handling methods of pressure vessels, helping you gain a comprehensive understanding of this important equipment.

Definition of Pressure Vessels

In a broad sense, pressure vessels refer to all closed containers that are subjected to pressure loads. However, in industrial practice, we usually define them according to the "Regulations for the Safety Supervision of Fixed Pressure Vessels". Containers that meet the following three conditions fall within the regulatory scope of these regulations:

The maximum working pressure ≥ 0.1 MPa;

Inner diameter ≥ 0.15m, and volume ≥ 0.025m³;

The filled medium is a gas, liquefied gas or a liquid with a maximum working temperature equal to or higher than the standard boiling point.

Note: All three conditions must be met simultaneously.

Classification of Pressure Vessels

Pressure vessels can be classified according to different criteria:

By work pressure classification:

1.Low pressure: 0.1 MPa ~ 1.6 MPa

Medium pressure: 1.6 MPa ~ 10 MPa

High pressure: 10 MPa ~ 100 MPa

Ultra-high pressure: > 100 MPa

2.By function:

Reaction vessel

Heat exchange vessel

Separation container

Storage container

The pressure vessels produced by Sinton Company are mainly storage containers and are widely used in various industrial settings.

3.Classified by hazard level:

First category: Low-pressure containers for non-flammable or non-toxic media

Type II: Containers for flammable or toxic media

The third category: Containers for extremely or highly hazardous media

Basic Parameters of Pressure Vessels

The core parameters of pressure vessels include:

Maximum working pressure: The highest pressure that may occur at the top of the container during normal use.

Design pressure: Not lower than the maximum working pressure, usually 1.05 to 1.1 times of it.

Maximum allowable working pressure: Determined by referring to the table based on temperature and the material of the flange.

Basic Structure of Pressure Vessels

A typical pressure vessel consists of the following components:

Cylinder body, head, flange, pipe connection, manhole, support

The reasonable design and selection of these components form the basis for ensuring the safe operation of the container.

Selection of Pressure Vessel Flanges

In practical applications, the selection of flanges is of utmost importance. Take a case from Sinton Company as an example:

Medium: Carbon Dioxide

Working temperature: 300℃

Work pressure: 10 MPa

We select the flanges in accordance with the HG/T 20615-2009 standard. We determine the type number and material of the flanges by referring to the table to ensure that they are suitable for high-temperature and high-pressure working conditions.

Selection of Bolts and Nuts

The selection of bolts and nuts also follows the standard specifications:

Selected in accordance with HG/T 20634-2009;

When the temperature is less than 300℃ and the nominal pressure is ≤ PN20, commercial grade hexagonal bolts and type I nuts can be selected.

When the temperature is ≥ 300℃ or the pressure is > PN20, special grade full-threaded studs (such as 35CrMo material) should be selected.

Sinton Company strictly selects components in accordance with standards to ensure the safety and durability of the connection parts.

Differences between Plate Flat Welded Flanges and Head-on Welded Flanges

Plate Flat Welded Flange (PL): Suitable for general media;

Socket-welded flange with neck (WN): Suitable for flammable, explosive, high-pressure, and toxic or harmful media.

Choosing the appropriate type of flange is a crucial step in preventing leaks and accidents.

Handling of Pressure Vessel Accidents

1. Common Causes of Accidents:

Excessive temperature and pressure

Manufacturing defect

Severe corrosion

Cracks or grooves

Incomplete or malfunctioning safety devices

2. Accident handling method:

Reduce the pressure in the container as soon as possible;

Activate the pressure relief device;

Stop adding materials to the reaction vessel and accelerate the cooling process.

Take measures to lower blood pressure and body temperature;

Stop the machine for maintenance when necessary.

Sinton Company reminds: Regular inspections and standardized operations are effective means of preventing accidents.

Through this introduction, we believe you have gained a more comprehensive understanding of pressure vessels. As a reliable partner in the industrial equipment field, Sinton Company will continue to provide professional, safe and efficient pressure vessel products and services. If you need further consultation, please feel free to contact us!