How to Join and Loosen Galvanized Pipe Fittings

Galvanized pipe fittings provide connections between pipes and allow for the changing of direction for the fluid flow, making them essential components of plumbing systems. They facilitate the transport of clean water for potable use, the efficient removal of wastewater, and gas distribution for heating and cooking in residential and commercial settings. They are manufactured from steel and coated with a protective zinc layer, making them resistant to corrosion and rust. The main features of galvanized fittings are:

• Corrosion resistance: The zinc coating acts as a barrier against corrosion, preventing the underlying steel from oxidizing and extending the fittings' life.
• Strength and durability: Galvanized pipe fittings are made from strong steel, capable of withstanding high pressures and mechanical stresses.
• Versatility: Available in various sizes and configurations, galvanized pipe fittings can accommodate various plumbing applications.
• Protecting potable water: The zinc coating prevents the release of harmful contaminants from steel into the water supply, ensuring the safety of drinking water.
• Durability in harsh environments: Galvanized pipe fittings are well-suited for outdoor applications and can withstand harsh weather conditions.

Table of contents

• Types of galvanized pipe fittings
• How to connect galvanized pipes without threads
• Connecting threaded galvanized pipes
• How to weld galvanized pipe
• How to loosen rusted galvanized pipe
• FAQs

Types of galvanized pipe fittings

The common fitting types used in galvanized pipes are:

• Couplings: Used to connect two pipes of the same diameter.
• Elbows: Change the direction of fluid flow by 90 or 45 degrees.
• Tees: Allow for branching of the pipe system, creating three connections.
• Nipples: Short pieces of pipe used for connecting fittings.
• Caps: Close off the end of a pipe.
• Unions: Provide a disconnectable joint for easy maintenance.

How to connect galvanized pipes without threads

Step 1: Take measurements

Galvanized pipes have rough edges from the zinc coating; hence, using the wrong coupling can cause leaks. A galvanized iron coupling connects non-threaded galvanized pipes to create a properly sealed joint.

First, use a tape measure to determine the width of each pipe. A common connector can be used if both pipes have the same width. If the widths differ, get a stepped coupling that gradually increases size to fit the adjoining pipe.

The inside width of the pipe is different from the outside. For example, if the outside width of the galvanized steel pipe is ¾", choose a connector that fits the inside width where the pipe and connector join. A pipe with a ¾" outside width would have a ½" inside width, so choose this connector size.

Step 2: Examine the layer

Check if the pipe's surface is rough. If yes, get a special connector for bumpy and uneven surfaces (Table 1). A smooth pipe surface means a common connector should be fine.

Table 1: Special vs common connectors comparison

Feature	Special connectors	Common connectors
Tolerance for uneven surfaces	Wide	Tight
Material	Hard (like malleable iron)	Soft (like zinc)
Durability	More durable	Less durable
Cost	More expensive	Less expensive

Step 3: Ready the pipe

Use a level to ensure the end of the unthreaded pipe is straight. If not, cut the galvanized pipe straight with a saw and smoothen the sides. Then, use a water-based cleaner to clean the pipe. Align the connector to the middle of the pipe joint and mark a line on each end of the connector with a grease pencil.

Step 4: Connect the pipes

Put one end of the non-threaded pipe into the connector and align the end with the pencil line on the pipe. Do the same with the second pipe and ensure the connector is centered between the two lines. Place a coupling bolt on each bolt hole and tighten the coupling bolts using a wrench or socket wrench. Ensure to tighten the bolts evenly.

Connecting threaded galvanized pipes

To connect threaded galvanized pipe, cover all the threads with pipe dope, or wrap the threads with PTFE plumber's tape. This helps in establishing a leak-proof connection. Once the connection is hand-tight, use one pipe wrench to keep the pipe steady and another to tighten the fitting.

How to weld galvanized pipe

Welding joins galvanized pipes together and helps in repairing cracks, breaks, or leaks in them. There are a few challenges associated with welding galvanized pipes:

• Zinc fume inhalation: When welding galvanized steel, the zinc coating vaporizes and forms zinc oxide fumes. These fumes can be hazardous if inhaled, causing respiratory problems. Proper ventilation and respiratory protection are essential.
• Weld porosity: The zinc coating can interfere with the welding process, leading to porosity in the weld (small cavities or holes within the welded joint, which can weaken the weld and compromise its structural integrity). This can compromise the strength and integrity of the joint. To prevent porosity, remove the zinc coating in the weld area.
• Reduced corrosion protection: Welding exposes the bare steel underneath the zinc coating, making it susceptible to corrosion. To protect the weld area, a zinc-rich primer or paint can be applied after welding.

How to loosen rusted galvanized pipe

While galvanized pipes are generally more corrosion-resistant than black iron pipes, they are not entirely immune to rust. Over time, the zinc coating on galvanized pipes can erode, exposing the underlying steel to corrosion. Perform the following steps to loosen rusted galvanized pipes:

1. Turn off the water supply to the pipe section being worked on. Apply penetrating oil where the threaded pipe joins the fitting that needs to be removed.
2. Place one pipe wrench on the lock nut and the other on the retaining nut. The lock nut is the nut that is closest to the fitting, and it is used to lock the fitting in place. The retaining nut is the nut that is furthest from the fitting, and it is used to hold the pipe in place. Turn the retaining nut in an anti-clockwise direction to loosen the connection.
3. Hold the fitting steady with one of the pipe wrenches and use the other pipe wrench to turn the loose pipe attached to the fitting. Turn the wrench on the loose pipe anti-clockwise to remove the galvanized fitting.
4. Move the wrench on the loose pipe to the pipe on the opposite side of the fitting that's being removed. Turn the wrench anti-clockwise again, and the fitting should detach. If more force is needed, place a pipe over the wrench handle and push it downwards.

Read our hvac fittings guide for more details on the use of galvanized fittings in HVAC.

FAQs

Do galvanized pipes need Teflon tape?

Yes, galvanized pipes need Teflon tape to create a watertight seal.

Can you heat a galvanized pipe to loosen it?

Yes, you can heat a galvanized pipe to loosen it because heat will cause the metal to expand, which can break the seal between the pipe and the fitting.