How to Select Pressure Vessel Heads Suitable for Specific Operating Conditions?

Do you know how to Select Pressure Vessel Heads Suitable for Specific Operating Conditions?

Pressure vessel heads are the core pressure bearing components of equipment such as tanks, reactors and heat exchangers; their selection directly impacts equipment safety, service life and operating costs.

Jetvision combines internationally recognised design standards with the requirements of different operating conditions to provide you with a comprehensive selection guide, enabling you to quickly identify the right product.

1. Main Types of Vessel Heads and Their Applications

Vessel heads of different structures vary significantly in terms of pressure bearing capacity, dimensions and manufacturing costs. Selection should be based on equipment pressure, installation space and operational requirements:

Elliptical Heads/Ellipsoidal Heads: The most widely used type globally, featuring uniform internal stress distribution, excellent pressure bearing performance and the best overall value for money.

Suitable for medium and medium high pressure applications, they are the preferred choice for chemical processing equipment, generalpurpose storage tanks, boilers and heat exchangers.

They have standard installation space requirements and offer excellent overall stability.

Hemispherical heads: These offer the most optimal mechanical structure and require the thinnest wall thickness for a given pressure, thereby effectively saving raw materials.

However, the manufacturing process is complex and the cost is relatively high, so they are mostly used in high pressure and ultra-high pressure equipment,

and are commonly found in high pressure reaction vessels, specialised energy storage containers and large scale pressure vessels.

Torispherical head: These have a relatively shallow overall depth, take up little installation space, are easy to manufacture and are cost-effective.

There is some stress concentration in the transition zone, and their pressure bearing capacity is relatively weak;

they are recommended for low pressure and atmospheric pressure equipment, and are suitable for storage tanks and separation equipment where space is limited and pressure requirements are not high.

Conical heads: Offer inherent advantages in flow guidance and discharge, and are available in two structures: with or without a folded edge.

Unflanged conical heads are only suitable for low pressure environments;

The flanged type offers superior pressure resistance and is primarily used at the base of equipment requiring discharge or flow guidance, as well as in hoppers and vessels connected to reducer pipes.

Flat heads: These have the simplest structure and lowest manufacturing cost, but offer the poorest pressure resistance; under equivalent pressure conditions, wall thickness must be significantly increased.

They are recommended only for atmospheric or extremely low pressure applications, and are commonly used as equipment manholes, handholes, and small low pressure end caps.

2. Selecting Materials Based on Operating Conditions

Selecting materials based on the characteristics of the medium, operating temperature and corrosion protection requirements is key to ensuring the long term, stable operation of equipment:

Ordinary media at ambient temperature with no corrosive properties: Carbon steel is recommended, as it is economical and practical, and meets the requirements of the vast majority of general industrial applications.

Corrosive media such as acids, alkalis and salt spray, as well as equipment used in the food, pharmaceutical and water purification industries: 304 and 316L stainless steel are preferred, as they are corrosion resistant and easy to clean.

Highly corrosive and specialised chemical media: Select highly corrosion resistant alloy materials such as duplex steel and nickel based alloys.

Low temperature operating environments: Use specialised low temperature steels or low carbon austenitic stainless steel to prevent low temperature brittle fracture.

High temperature operating conditions: Use heat resistant alloy steel or high temperature stainless steel to ensure structural strength at high temperatures.

3. Key Considerations

Installation space: In confined spaces, torispherical heads are the preferred choice; where space is ample, elliptical heads are preferred for their superior overall performance.

Manufacturing and cost: For standard operating conditions, standard elliptical heads are preferred to balance performance and cost;

Torispherical heads may be selected for large volume, low pressure equipment;

Hemispherical heads may be selected for high pressure special purpose equipment to reduce overall material usage.

Standards Compliance: All products can be manufactured in accordance with international standards (ASME VIII-1, API 650, EN 13445 / GB/T 25198) to meet equipment acceptance requirements in different countries and regions.

Structural Details: All standard tank heads are equipped with standard straight edge sections to avoid potential hazards such as weld overlap and stress concentration, thereby enhancing weld quality and operational safety.

4. In Summary

First, determine the vessel head shape based on the working pressure;

Then, select the raw materials according to the medium, temperature and corrosion protection requirements;

Finally, make the final selection based on installation space and budget;

All products support customised dimensions, materials and processes to suit various non-standard pressure vessel projects.