Malleable Cast Iron Threaded Fittings
Malleable cast iron threaded fittings connect pipes through female and male threads. Depending on the design, pipe nipples, reducing nipples, couplings, elbows, manifolds, wall plates and reducers are available for different pipe routes.
Choose malleable cast iron threaded fittings by design
Threaded fittings made of malleable cast iron are pipe connection components for lines carrying liquids or gases. The category fact cards list sanitary, heating and gas installations as well as industrial applications. The geometry of the connection is the first consideration: Should a pipe be extended, connected through female threads, routed around a corner or divided into several lines? The connection type, thread size and, for pipe nipples, the length are then compared with one another.
The designations help with the initial classification. AG means male thread, while IG means female thread. An entry such as 1/2 inch IG x 1/2 inch AG therefore describes two different connection sides. A pipe nipple with AG x AG, on the other hand, has two male threads. The thread type must match on each mating part.
Designs and their functions
The range includes straight connectors, changes of direction and branches. The differences lie less in a general label than in the shape and arrangement of the threads.
Pipe nipples
The fact cards describe pipe nipples with two male threads and different lengths. They create a straight connection between matching mating parts.
Couplings and reducing nipples
Couplings join two female threads. A reducing nipple combines female and male threads; this design appears in the product cards, for example as 1 1/2 inch IG x AG and in a 2-inch version.
Elbows and manifolds
Elbows and bends continue a pipe in another direction. Elbow manifolds, T-pieces and cross fittings add branches or several connection sides.
Compare connection types, thread sizes and lengths
Check AG and IG first
One pipe nipple in the selection is specified as 2 inch AG x 2 inch AG and 1000 mm. Another galvanized pipe nipple is described as 3/4 inch AG x 3/4 inch AG and 80 mm. These examples show why the nominal size alone is not enough: The thread type at both ends and the overall length must also match the existing line.
Select the length according to the installation location
For long straight runs, the fact cards include 500 mm and 1000 mm, among other lengths. For short connections, a pipe nipple with 2 inch AG x 2 inch AG and 40 mm is also listed. Other cards specify 180 mm for 3/4 inch AG x AG. Length is therefore a separate selection criterion: It determines how much distance should be bridged between the mating parts and how much room is available for installation.
For mixed connections, read the order of the specifications: The 90-degree elbow with 1/2 inch IG x 1/2 inch AG connects one female-threaded side and one male-threaded side. With the 45-degree elbow of the same nominal size, the change of direction is shallower. For comparison with larger connections, the product cards also list 1 inch IG x 1 inch AG and 2 inch IG x IG.
Classify malleable cast iron and galvanized versions
Read material specifications separately
For wall plates, elbow manifolds, cross fittings, couplings and elbows, malleable cast iron appears in the product name or description. The pipe nipple cards, in contrast, specify steel or galvanized steel; these items also state a galvanized surface. The versions can therefore be distinguished using the respective product specification without transferring material properties to every variant.
One wall plate is described as a 90-degree version with 3/4 inch IG x 3/4 inch IG and is listed for wall mounting. Another wall plate has 1 inch and 90 degrees in its name. For cross fittings, the fact cards specify four female threads; one example is listed as 1/2 inch IG and another as 1 1/2 inch IG. These designs are therefore selected by the number of connections and the thread size.
Plan changes of direction and branches
The product cards include 45-degree and 90-degree elbows for changing direction. A short 90-degree bend with 2 inch IG x IG is described as a space-saving design. The 1 inch IG x 1 inch AG version has mixed threads. Before ordering, compare the fitting with the pipe route: A 45-degree elbow changes direction less sharply than a 90-degree elbow, while a bend, elbow manifold and cross fitting each specify a different connection geometry.
Elbow manifolds have several connection specifications. One product is listed as 3/4 inch and galvanized; another specifies 1/2 inch IG x 1/2 inch IG x 1/2 inch IG. A cross fitting joins four female threads. T-pieces and wall brackets are further designs within the category. The key question is whether a line should branch, be attached to a wall or simply be routed around a corner.
Prepare sealing and installation
The product descriptions point out that the threaded connections are not self-sealing. They name PTFE tape or hemp for sealing. This detail is part of the selection process: A fitting may match in thread type, nominal size and design and still require its own sealing material.
- Measure the existing mating side and distinguish between female and male threads.
- For pipe nipples, compare the required length with the available installation space.
- For elbows, determine the desired change of direction: 45 or 90 degrees.
- For manifolds, check the number of required connection sides and their thread sizes.
- Plan suitable sealing material such as PTFE tape or hemp for the threaded connection.
This keeps the decision grounded in the information for the respective product. For variants with the same nominal size, the design, IG or AG connection and length can make the decisive difference.
Subcategories by connection type
The subcategories group the designs so that searching for the right geometry remains clear. The following areas cover straight connections, closure, female threads and changes of direction.
Double nipples + pipe nipples
Straight components with male threads for pipe connections and defined lengths.
Double nipples + pipe nipplesElbows + bends
Designs for 45-degree or 90-degree changes of direction in pipe routing.
Elbows + bendsReducers, unions, manifolds and wall brackets, as well as accessories, are also organized as separate areas. Reducers connect different thread sizes, unions support detachable connections and manifolds divide a line. For these designs, the connection specifications must likewise be taken from the respective product card.
Examples from the product cards
The following examples show how design, material specification, connection and length are read together. The images belong to the linked product page in each case.
Pipe nipple, 2 inch AG x 2 inch AG, 1000 mm
The fact card lists steel as the material and a galvanized version. Two male threads and the 1000 mm length describe the connection type and the distance bridged.
Wall plate, 90 degrees, 3/4 inch IG x 3/4 inch IG
This malleable cast iron wall plate is described with 90 degrees, 3/4 inch IG x 3/4 inch IG and a galvanized surface. The product card lists wall mounting as a feature.
Malleable cast iron reducing nipple, 2 inch
The card identifies it as a malleable cast iron reducing nipple and specifies a galvanized surface. The design is intended to connect fittings with female and male threads.
As another comparison, a galvanized pipe nipple with 3/4 inch AG x 3/4 inch AG and an 80 mm length is listed: Pipe nipple, 3/4 inch, 80 mm. Comparing lengths and connection types makes it easier to assign the fitting to the existing pipe section.
Related categories and range classification
Malleable cast iron is a separate material group within threaded fittings. For material comparison, the neighboring categories include 316 stainless steel and brass. The higher-level classification is sanitary and irrigation, allowing the fittings to be considered together with other pipe and connection components.
316 stainless steel threaded fittings
Neighboring material category for comparison within threaded fittings.
316 stainless steel threaded fittingsBrass threaded fittings
Another neighboring material category for threaded fittings.
Brass threaded fittingsFAQ about malleable cast iron threaded fittings
What do IG and AG mean on a threaded fitting?
IG means female thread and AG means male thread. The combination 1/2 inch IG x 1/2 inch AG therefore describes two different connection sides. With AG x AG, both ends have male threads.
Which length is suitable for a pipe nipple?
The length is selected according to the distance between the mating parts and the available installation space. The fact cards list, for example, 40 mm, 80 mm, 180 mm, 500 mm and 1000 mm with the respective connection sizes. The specific product specification is decisive.
When is a coupling suitable instead of a pipe nipple?
A coupling is used when two pipe ends are joined through female threads. A pipe nipple with two male threads fits mating parts with female threads. The decision therefore depends on the threads on the existing pipe ends.
When is a 45-degree or 90-degree elbow suitable?
A 45-degree elbow continues the line with a shallower change of direction. A 90-degree elbow turns it at a right angle. In addition, the IG or AG type and the nominal size on both connection sides must match the existing installation.
How are the threaded connections sealed?
The product descriptions point out that the threads are not self-sealing. They name PTFE tape or hemp as sealing materials. The preparation required in an individual case depends on the connection and the material used.
How can I identify a branch?
Elbow manifolds, T-pieces and cross fittings have several connection sides. The fact cards describe an elbow manifold with three thread specifications and a cross fitting with four female threads. Compare the number of connections, thread type and nominal size when choosing.
Further reading
Magazine article
The linked article discusses choosing tools and accessories for painting work and adds a practical perspective on preparing for tasks.
Painting tools & accessories: How to choose the right helpers for painting