Knowledge for Threaded Cast Iron Fitting

by | Mar 9, 2022 | Industry Knowledge

Cast iron fittings are components used to join cast iron pipelines and reverse their direction. These are used for the construction of household and industrial water, gas, and heat distribution systems.

Features of the production

Threaded cast iron fittings are produced from grey cast iron with the addition of soft graphite. To protect against corrosion, finished products are coated with nickel, enamel or bituminous composition.

The result is a material that can withstand pressures up to 25 bar and temperatures up to 300⁰C.

Elements made from other types of cast iron or not galvanized are cheaper, but their scope is not so universal.

Advantages and disadvantages

Cast iron threaded fittings have the advantages of durability and wide applications. They bond easily to plastic and steel.Brittleness is one of the disadvantages of cast iron fittings. Due to the difference in electrochemical processes, it is not recommended to use cast iron fittings with copper pipes, as the junction will be subject to increased corrosion.

Types of cast iron fittings

Cast iron threaded fittings are produced in various types:





Plugs, etc.

Cast iron threaded fittings are manufactured by shaped casting. The thread is applied using a lathe. Fittings are available in sizes ranging from 1/4″ to 4″. The wall thickness of the connecting elements is 2.5-5.5 mm.


Cast iron threaded fittings require open-ended, adjustable wrenches to be installed. It is possible to use a sealing gel or a sealant that is pre-wound on the external threads of the joined elements. An impact wrench is used to tighten the connection, then the lock nut is tightly tightened.

Jianzhi Casting Group manufactures cast iron threaded fittings of excellent quality. Cast iron threaded fittings simplify installation and reconstruction of pipeline systems, ensure high-quality connections and trouble-free operation of the pipeline network for a period of 50 years.

Cast iron threaded fittings are strong and durable connecting elements. However, it is worth remembering that trouble-free operation of communications can only be guaranteed if it was built using certified products.

Cast iron fittings are still widely used in the construction of pipelines, despite the fact that cast iron communications are a thing of the past. Their unfading popularity can be attributed to their long service life of 60 to 80 years and their high strength.

Cast iron fittings are connecting elements used to form sewer networks, water pipes, gas mains and heating systems.

Along with the construction of pipelines, shaped elements made of cast iron find wide application in industry and the extractive industries. Cast iron fittings are represented in modern plumbing market by tees, crosses, couplings, and bends.

The role of cast iron fittings in the pipeline system cannot be overestimated. With their help, pipes of different sections are connected, and they also change the horizontal and vertical direction of the pipeline system.

Fittings are perfect for joining sewer pipes to plumbing, forming knots and turns of any complexity, as well as for installing pipelines with large height differences. As these elements can be used both internally and externally, they are quite versatile.

Cast iron fittings are divided according to several criteria, the main of which is the functional purpose of the part.

Couplings are designed to connect pipes of the same diameter.

Transitional couplings are used for the installation of pipes of various sizes.

Elbows are used to change the direction of the pipeline and are available with 30, 45, 60 and 90-degree swivel angles.

Tees allow branching of the pipeline and are used to connect plumbing, washing machines and dishwashers to the sewer system.

Crosses are used to form two branches coming out of the same branch.

Plugs, flanges and caps are mounting parts and are designed to block the end sections of the pipeline, for example, heating radiators.

Fitting – a fitting designed to connect a metal pipe with a plastic hose

The size of a fitting is also an important criterion for classification. Currently, 11 standard sizes are being produced, varying in the width of the conditional passage, which varies from 8 to 100 mm.

According to the generally accepted scale of sizes, the parameters of the pipe vary from 1/4 to 4, while the accuracy class corresponds to the letter B. Products also differ in wall thickness.

The minimum thickness value is 2.5 mm, which indicates the absolute value, excluding the threaded groove.

After the sealant is wound and the surface is treated with sealant, the parts are twisted along the applied composition and tightened with keys. At the same time, the lock nut is tightly fitted to the junction and is well twisted.

An important condition for a reliable connection is the presence of a sealant between the locknut and the thread, so its use cannot be neglected.

The final assembly step will be the painting of the connection, which is performed only if there is no factory protective layer on the fitting.

Due to the versatility and time-tested design, the installation of cast iron fittings can be done independently.

However, to achieve the desired result in creating a reliable and airtight sewer, you should listen to the opinion of experienced plumbers.

Installation of cast iron parts must be done with an assistant. This requirement is due to the large weight of the pipeline elements and the difficulty of aligning the parts when tightening the locknuts.

It is not recommended to neglect sealing materials or use them in insufficient quantities. This can lead to leakage and the spread of an unpleasant odor from the sewer.

On horizontal sections of sewer networks, it is advisable to install tees with a small junction angle not exceeding 45 degrees. This will reduce the chance of clogging and eliminate the need for premature repairs to the system.

During installation, cast iron pipes must be attached to the bases by means of brackets-holders. This will reduce the weight load on the joints and prevent deformation of the joints and sagging of the pipes.

Despite the fact that cast iron tees and couplings have been used for a long time as connecting elements of sewer systems, it is highly undesirable to use them for sewage removal. This is due to the tendency of cast iron to accumulate dirt and mucus on its surface, which leads to clogging of the system and the appearance of an unpleasant odor from the revision sleeves. For the construction of sewer networks, it is better to use polypropylene products.

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