Difference between malleable iron and forged iron pipe fittings?

Malleable Iron Pipe Fittings

We get this question a lot from customers who are often trying to determine the difference between malleable iron vs forged iron pipe fittings, and whether they should use malleable iron fitting or forged iron threaded fitting or socket weld fitting. Malleable iron fittings are lighter fittings in 150# and 300# pressure class. These malleable iron pipe fittings are commonly used in plumbing, fire protection, and light industrial systems where moderate pressure and flexibility are required. They are made for light industrial and plumbing use up to 300 psi. Some malleable fittings such as floor flange, lateral, street tee and bullhead tees are not commonly available in forged iron.

Malleable iron offers more ductility that is often required in light industrial use. Malleable iron pipe fitting is not good for welding (if you ever need to weld something to it), which limits its use in high-pressure industrial piping systems.

See the table below for pressure and temperature rating of malleable iron fitting;

Malleable Iron Fitting Rating

Malleable iron fittings, also called black iron fittings, are available up to 6 inch nominal pipe size, though they are more common to 4 inches. Malleable fittings include elbows, tees, couplings and floor flange etc. Floor flange is very popular to anchor items to the ground. Trupply sells wide variety of malleable iron fittings ONLINE that can be found here.

Forged Iron Pipe Fittings

Forged Iron Pipe Fittings are available as socket weld pipe fitting or threaded pipe fitting. Forged fittings are made of A105 (carbon steel), stainless steel or nickel alloy. These fittings are thicker, heavier and are intended for heavy industrial use. Forged Iron Pipe Fittings are available in 2000#, 3000#, 6000# and 9000# pressure class. These fittings are more common in 3000# and 6000# (90% of the time). This wide pressure range is a key reason forged iron pipe fittings are preferred over malleable iron fittings in demanding industrial applications. This wide pressure range is a key reason forged iron pipe fittings are preferred over malleable iron fittings in demanding industrial applications. Threaded pipe fittings and socket weld pipe fittings are available up to 4 inch nominal pipe size. When comparing threaded pipe fittings vs socket weld pipe fittings, socket weld fittings are generally used where leak resistance and strength are critical. See the table below for pressure and temperature rating of these fittings.

Trupply sells these fittings for convenient online shopping here.

Video Overview

Video below gives an overview of malleable iron and threaded pipe fittings.

Malleable iron fitting

Threaded pipe fitting

socket weld fitting

Here is the cost comparison of different pipe fittings.

Malleable Iron Fitting - $

Threaded Pipe Fitting - $$$

Socket Weld Pipe Fitting - $$

Buttweld pipe fitting - $$

Forged Iron Threaded or Socket Weld Fittings are more expensive in sizes bigger than 2 inch compared to their malleable iron or butt weld counter parts.

Cost differences become more noticeable when comparing malleable iron vs forged iron pipe fittings in sizes above 2 inch.

Malleable Iron Fitting and Threaded Pipe Fitting differ in material metallurgy, pressure class and application . It is important to select appropriately between them for the intended application. 

If you have any question about these fittings or want to buy one, call Trupply at 281.516.8100

How to Choose Between Malleable Iron and Forged Iron Pipe Fittings

If the application involves low pressure, non-critical service, and ease of installation, malleable iron pipe fittings are usually sufficient.
For high-pressure, high-temperature, or industrial service, forged iron pipe fittings such as threaded or socket weld fittings provide better strength and long-term reliability.

Frequently Asked Questions

1. Where are malleable iron pipe fittings typically used?

Malleable iron pipe fittings are commonly used in plumbing, fire protection, HVAC, and light industrial piping systems where operating pressure is low to moderate and ease of installation is required.

2. What applications are forged iron pipe fittings used for in industrial plants?

Forged iron pipe fittings are used in high-pressure and high-temperature systems such as oil and gas pipelines, chemical processing units, power plants, and critical industrial service lines.

3. Why do industrial facilities choose forged iron fittings over malleable iron fittings?

Industrial facilities prefer forged iron pipe fittings because they offer higher strength, better pressure ratings, and improved reliability under demanding operating conditions.

4. What is the difference between threaded and socket weld forged iron fittings?

Threaded fittings are used where frequent disassembly or maintenance is required, while socket weld fittings provide stronger, leak-resistant joints for high-pressure and vibration-prone systems.

5. Why do buyers source malleable and forged iron pipe fittings from suppliers like Trupply?

Buyers choose established suppliers like Trupply for certified materials, consistent quality, reliable inventory, and technical support that helps ensure correct fitting selection for each application.