Home Plumbing What Does FIP Mean in Plumbing? A Complete Guide

What Does FIP Mean in Plumbing? A Complete Guide

by Michael Blount

Plumbing systems are complex, comprising many different fittings and connectors. When browsing plumbing aisles or reading catalogs, you may come across the abbreviation “FIP.” So what exactly does FIP stand for and why is it important for plumbing applications?

FIP stands for “Female Iron Pipe” and refers to a specific type of threaded fitting used to join pipes, valves, and fixtures in plumbing and heating systems. In this comprehensive guide, we’ll explore everything you need to know about FIP fittings, from definitions and characteristics to proper installation and maintenance.

FIP Fittings

FIP, short for Female Iron Pipe, refers to a fitting with interior threads that allow it to connect to male threaded fittings and pipes. FIP fittings are commonly used in both residential and commercial plumbing applications.

Some key points about FIP in plumbing context:

  • FIP stands for Female Iron Pipe.
  • It is a type of fitting with interior threads to connect with male threaded components.
  • Used extensively in plumbing systems for connecting pipes, valves, and fixtures.
  • Allows for secure, leak-proof joints in pressurized pipe systems.

Below is a table showing common abbreviations for different plumbing fittings:

Abbreviation Fitting Name
FIP Female Iron Pipe
MIP Male Iron Pipe
FPT Female Pipe Thread
MPT Male Pipe Thread
FGH Female Garden Hose
MGH Male Garden Hose

Now that we’ve covered the basic definition, let’s explore FIP fittings in more detail.

What Are FIP Fittings?

FIP, or Female Iron Pipe, fittings have threaded interior openings that allow them to connect to male threaded components. The female threads are tapered and conform to national standards for pipe threads. FIP fittings are available in a range of materials including galvanized steel, black iron, brass, and more.

Some key characteristics of FIP fittings:

  • Interior threads – The inside of the fitting has tapered threads to connect to male threaded pipes and fittings.
  • Standard thread dimensions – FIP threads follow national standards for pipe thread sizes and pitches. This ensures compatibility and leak-proof seals.
  • Variety of materials – FIP fittings come in galvanized steel, black iron, brass, and other materials for compatibility across many applications.
  • Withstands pressure – Properly installed FIP fittings can withstand high pressures in heating, water, gas, and industrial piping systems.

It’s important to distinguish between FIP and FPT fittings. While related, they are designed for different purposes:

  • FIP – Female Iron Pipe with tapered, interior threads. Used to connect pipes and fittings in pressure systems.
  • FPT – Female Pipe Thread has straight machine threads and are used to connect to external threaded pipes or nipples. Not suitable for pressurized systems.

In summary, FIP fittings have tapered interior threads that allow secure connections for pressurized gas, water, and heating systems.

Uses of FIP Fittings

FIP fittings are commonly used in both residential and commercial plumbing applications. Here are some of the most common uses for FIP threaded fittings:

  • Connecting water heaters – FIP fittings allow heaters to be securely plumbed into water supply and output lines.
  • Gas line connections – FIP is ideal for connecting gas appliances like stoves using black iron or galvanized steel pipes and fittings.
  • Iron pipe joints – FIP fittings join together threaded iron pipes in water, gas, and heating systems.
  • Connecting valves – FIP fittings allow valves like ball, gate, and globe valves to be installed in pressurized pipe systems.
  • Transitioning materials – FIP fittings join dissimilar materials like connecting copper tubing to galvanized pipe.
  • Appliance connections – Many appliances like water filters and RO systems use FIP fittings for inlet and outlet plumbing.
  • Attaching fixtures – Faucets, showerheads, and other fixtures often have FIP inlets to connect to water supply pipes.

The main advantage of FIP fittings is their ability to create secure, leak-proof joints even under high pressure. This makes them ideal for critical gas line, water line and heating system connections.

FIP vs MIP Fittings

MIP stands for Male Iron Pipe and is the counterpart to the female FIP fitting. The main differences between these two common threaded fittings are:

  • FIP – Has interior threads to mate with male threaded components.
  • MIP – Has exterior threads to connect with internally threaded fittings.
  • FIP – Common for valves, fixtures, and appliances.
  • MIP – Used for pipe runs and to connect pipes and fittings.
  • FIP – Receiving side of a threaded connection.
  • MIP – Supply side of a threaded connection.

So in summary:

  • FIP has interior threads to connect to male threaded pipes, nipples, and fittings.
  • MIP has exterior threads to connect to fittings with interior threads like FIP.
  • FIP fittings are often attached to valves and appliances while MIP fittings connect piping.

FIP and MIP create secure threaded connections crucial for pressurized plumbing and heating systems. Both are tapered and follow national pipe thread standards.

Other Common Plumbing Fittings

FIP fittings are designed specifically for creating watertight, high-strength threaded connections. But you may encounter other fitting types for various plumbing applications:

  • FPT – Female Pipe Thread has straight threads for connecting pipes externally.
  • MPT – Male Pipe Thread has external straight threads to connect to internallly threaded components.
  • FGH – Female Garden Hose has interior threads to connect with male hose fittings.
  • MGH – Male Garden Hose has exterior threads to mate with female hose connectors.
  • PVC – Plastic PVC fittings use solvent welding rather than threads to join pipes.
  • PEX – Cross-linked polyethylene PEX tubing uses compression or crimp fittings for connections.
  • Push-to-Connect – A push-in fitting that creates a seal without threads or clamps.

While FIP fittings are made for high-pressure connections, other fitting types like FGH, PVC, and PEX have specialized non-threaded methods for creating leak-proof joints.

Key Points About FIP Fittings

To summarize the key points about Female Iron Pipe fittings:

  • FIP stands for Female Iron Pipe threaded fitting
  • Has tapered interior threads to connect to male components
  • Materials include galvanized, black iron, brass, and more
  • Creates high-strength, pressure-tight joints
  • Used for water heaters, gas lines, valves, appliances, etc.
  • Distinguished from FPT and other fittings
  • Available in a range of standard sizes
  • Requires sealant or tape to create leak-free connections

Tips for Working with FIP Fittings

When working with FIP fittings, follow these tips to ensure correct installation and prevent leaks:

  • Clean threads – Use a wire brush or thread chaser to remove any dirt or damage from fitting and pipe threads.
  • Apply pipe sealant – Use Teflon tape or pipe thread sealant to lubricate and seal the threaded connection.
  • Hand tighten – Initially hand tighten the FIP fitting as much as possible to prevent cross-threading.
  • Wrench tighten – Finally, use properly sized wrenches to finish tightening the joint 1-2 turns past hand tight.
  • Check for leaks – Pressurize the system and check for any leaks which indicate the fitting needs additional tightening.
  • Avoid overtightening – Overtightening can crack the fitting. Tighten only as much as needed to create a leak-free seal.

Following proper FIP installation procedures will produce leak-free joints that stay secure over time. Always refer to local plumbing codes for additional requirements.

Step-by-Step FIP Installation

Here is a step-by-step guide to properly install a FIP fitting:

  1. Clean male and female threaded areas with a wire brush and thread chaser. Remove any debris, rust or damaged threads.
  2. Apply 2-3 wraps of Teflon tape or pipe thread sealant to the male threads. Ensure tape covers all threads but does not overly accumulate.
  3. Hand tighten the FIP fitting onto the male threaded pipe. Turn clockwise until hand tight.
  4. Place properly sized wrenches on the fitting and threaded component for leverage.
  5. Tighten the fitting 1-2 turns past hand tight. For iron fittings, tighten 2/3 to 1 full turn with wrenches.
  6. Verify alignment of the fitting. Overly misaligned joints can indicate improper tightening.
  7. Pressurize system and check for leaks. Turn off water, dry the joint, and tighten further if any leaks are found.
  8. Label or mark the fitting with pipe type, size and orientation once fully tightened and leak tested.

A Brief History of FIP Fittings

The history of FIP fittings follows the evolution of threaded pipe connections used in plumbing, gas, and mechanical systems. Some key developments include:

  • Early 1800s – Threaded cast iron pipe appears as an alternative to lead pipe for water supply lines. This spurs the need for threaded fittings.
  • Late 1800s – Malleable iron fittings allow easier pipe fabrication. FIP and MIP fittings become common.
  • Early 1900s – National Pipe Thread standards are developed. This ensures consistency across threaded fittings from different manufacturers.
  • Mid 1900s – FIP fittings are widely used in commercial and residential buildings for water, gas, heating, and indoor plumbing systems.
  • Today – FIP remains the standard for threaded fittings, now available in stainless steel, chrome-plated brass, and advanced polymer materials.

Although materials and manufacturing have improved, FIP fittings today serve the same crucial role as over a century ago – creating strong, leak-free connections for pressurized fluid systems.

Why Proper FIP Installation is Important

Installing FIP fittings properly is critical for creating safe plumbing and gas systems. Here are some key reasons why following best practices with FIP fittings is so important:

  • Prevent leaks – Leaks from improperly installed fittings can lead to water damage, mold growth, and even gas leaks or explosions.
  • Avoid joint failure – Poor installation can result in joints loosening over time, causing catastrophic failures.
  • Maintain pressure rating – Proper FIP installation maintains the designed pressure rating for the system.
  • Reduce corrosion – Keeping joints tight prevents crevice corrosion within the threaded connection.
  • Comply with codes – Improper FIP installation often violates plumbing and mechanical codes.
  • Maximize service life – Correct FIP joint tightening ensures leak-free service for the lifetime of the plumbing system.

While it may seem simple, properly creating FIP joints requires attention to detail, proper materials, and correct tightening. Taking the time to correctly install FIP fittings results in safer, more reliable plumbing systems.

FIP Fittings and Plumbing Codes

When installing plumbing and gas systems, it is crucial to follow all relevant building, mechanical, fuel gas and plumbing codes. For FIP fittings, some key code requirements include:

  • Pipe types – Codes dictate what pipe materials are approved for water, gas, and heating systems. This affects compatible FIP fitting materials.
  • Fitting approvals – FIP fittings must be approved for use with the piping system. Unapproved fittings often violate code.
  • Thread sealants – Some codes prohibit certain thread compounds for potable water or gas piping.
  • Sizing – FIP fittings must be appropriately sized for the pipes and meet code flow requirements.
  • Pressure testing – Installed systems with FIP fittings may need to be pressure tested to verify code compliance.
  • Orientation – Fittings must be installed in the correct orientation to avoid violating directional flow codes.
  • Professional installation – In some areas, codes require licensed pros for installation of gas lines and certain plumbing systems.

Always check your local plumbing authority regarding any codes and permits for the installation of FIP fittings in your plumbing system.

As one of the most widely used threaded fittings, FIP shows up in many key statistics related to the plumbing industry:

  • $40 billion – Estimated annual revenue of US plumbing industry
  • 17% – Expected growth in plumbing fitting manufacturing by 2027
  • 14-15% – Estimated portion of plumbing fittings revenues from threaded fittings
  • 42 gallons – Average daily water usage per person in US homes
  • 350,000 – Approximate number of active plumbers and pipefitters in the US
  • 51% – Percentage of US households who had plumbing repairs in past year
  • 25-50 years – Typical service life of a residential water heater when properly installed with FIP fittings
  • 2.2 million – Number of miles of natural gas distribution mains in US

These statistics demonstrate the massive scale of the plumbing industry and highlight the importance of proper fittings like FIP to create safe and reliable pipe systems across the country.

Tips for Selecting FIP Fittings

When purchasing FIP fittings, keep these tips in mind:

  • Choose fittings approved for the type of system – potable water, gas, heating, etc.
  • Match the material to the piping – brass for copper tubing, galvanized steel for steel pipe, etc.
  • Verify the pressure rating meets the system pressure.
  • For potable water, lead-free brass and polymer fittings are recommended.
  • Black iron fittings suffice for gas lines, heating and industrial piping.
  • Request certified, code-approved fittings from reputable plumbing suppliers.
  • Ensure the fitting dimensions match the pipe sizes they will connect.
  • Purchase a few extra fittings in different sizes for repairs. They have a long shelf life.

Selecting the optimal FIP fittings for an application prevents leaks, maintains pressure capability, and ensures compliance with plumbing codes. Consult manufacturers for specific recommendations.


FIP, short for Female Iron Pipe, refers to a ubiquitous fitting used extensively in residential and industrial plumbing applications. The interior threads allow FIP fittings to create secure, pressure-tight joints by connecting with male threaded components.

Following proper installation procedures and building codes when working with FIP fittings ensures leak-free operation and maximum safety. While often taken for granted, these unassuming threaded fittings play an essential role in supplying water, gas, heat, and other piped services reliably and efficiently to homes, businesses and factories alike.

You may also like

Leave a Comment

About Us

We’re your go-to source for all things related to making your home better. Our blog is your one-stop destination for easy-to-understand home improvement ideas.

Whether you’re a DIY enthusiast or just looking for simple ways to enhance your living space, we’ve got you covered.

Decor & Design

Editors' Picks