26 Mar, 2026

Tube Purge Kit vs Pull-Through Purge Kit: Pros, Cons + When to Use Each

If you’re TIG welding stainless steel, duplex, or any corrosion-resistant alloy, you already know that a proper back purge is non-negotiable. Skip it, and you’ll end up with sugaring, oxidation, and welds that won’t pass inspection – or worse, won’t hold up in service.

But here’s where it gets interesting: not all purge kits work the same way, and picking the wrong one for the job can waste your argon and time, leaving you with an inconsistent purge. The two most common options are a tube purge kit (plug-style) and a pull-through purge kit (dual-seal style). Each has a clear sweet spot – and clear limitations.

This guide breaks down both so you ensure the right purge welding kit from day one.

How a Tube Purge Kit Works

A tube purge kit is the workhorse of small-diameter tube fabrication. It’s a simple setup: two plugs – one with a gas inlet and diffuser, the other with an exhaust port – that press into each end of your tube or pipe.

You connect your argon line to the inlet plug, push both plugs into the open ends of the workpiece, and let the gas fill the internal volume. The diffuser spreads argon evenly through the tube while oxygen exits through the exhaust. Once the atmosphere inside is clean (ideally below 50 ppm O₂ for sanitary work), you’re ready to weld.

Most quality tube purge plugs are made from UHMW polyethylene or high-grade silicone, both of which handle welding heat well and create a positive seal against the tube wall. Kits typically come in colour-coded sizes ranging from 1″ to 4″ OD, covering the most common tube diameters used in food, beverage, dairy, and pharmaceutical piping.

If you’re unsure which size kit matches your tube or pipe specification, our guide on Dairy tube vs Schedule 10 vs Schedule 40 pipe explains the differences and helps you pick the right purge kit for each.

Tube Purge Kit: Pros

Fast to set up. Push the plugs in, connect your gas, and you’re welding. On short tube runs, you can be purging in under 30 seconds.
Affordable. A decent plug kit covering common tube sizes costs a fraction of what you’d spend on a pull-through system.
Portable. Most kits fit in a soft case that lives in your toolbox or the back of the ute. Great for mobile welders and site work.
Ideal for orbital welding. Tube purge plugs pair perfectly with orbital weld heads in production environments where you’re making repetitive welds on the same tube size.
Reusable. Quality plugs are virtually indestructible. Replace the silicone sealing rings when they wear, and the kit keeps going.

Tube Purge Kit: Cons

Limited to an open-ended tube. Both plugs need to go into an open end. If the tube is already tied into a system or there’s only one accessible opening, a plug kit won’t work.
Purges the entire volume. On long tube runs, you’re filling metres of pipe with argon just to protect a few centimetres around the weld. That adds up quickly – especially at today’s gas prices. For tips on cutting that cost, have a read of how to reduce argon usage when purging pipe.
Size-specific. Each plug fits a narrow range of internal diameters. If you’re working across various pipe sizes, you’ll need a larger kit or multiple sets.

How a Pull-Through Purge Kit Works

A pull-through purge kit (sometimes called a dual-seal system) takes a different approach. Instead of sealing the entire tube, it creates a small, isolated purge zone right around the weld joint.

The kit consists of two silicone sealing discs connected by a flexible spacer (typically 120–200mm long), with a gas inlet between them. You feed the unit into one end of the pipe, pull it through to the weld location using a tow wire, then introduce argon into the sealed zone between the two discs. Because you’re only purging that short section, not the whole pipe, the volume of gas required drops dramatically.

Once the zone hits your target oxygen level, you weld. When you’re done, you simply pull the unit through to the next joint and repeat.

Pull-Through Purge Kit: Pros

Massive gas savings. You’re purging a zone of 120–200mm instead of the entire pipe length. On long runs, this can reduce argon usage by 70–80%.
Handles bends and elbows. The flexible spacer and soft silicone discs navigate 90° bends without getting stuck – something plug kits can’t do.
Works on long, closed-in pipe runs. Because you pull the unit through from one end, you don’t need access to both ends of the pipe near the weld. This is a major advantage for installed pipework.
Fast purge times. The small volume means you can reach weldable oxygen levels in under two minutes on most pipe sizes.
Covers a wide diameter range. Interchangeable disc sizes mean one system can handle pipes from 25mm up to 300mm+ internal diameters.

Pull-Through Purge Kit: Cons

Higher upfront cost. A quality dual-seal system with a range of disc sizes is a bigger investment than a basic plug kit.
Not suited to very short tubes. If you’re welding short ferrules or stubs, there may not be enough length to position the unit properly.
Requires a tow wire. You need to feed a wire or cord through the pipe first to pull the unit into position. On straight sections, this is quick, but on complex geometry with multiple bends, it takes patience.
More components to manage. Discs, spacers, tow brackets, gas lines – there are more bits to keep track of compared to a simple plug set.

When to Use Each

Choosing between the two really comes down to the type of work you’re doing day to day.

Choose a tube purge kit when:

You’re working with short tube sections or cut lengths on a bench.
You’re doing orbital welding in production where setup speed matters.
You’re welding sanitary tubes in dairy, food, or pharmaceutical applications.
Budget is tight and you need a reliable, affordable purging solution.
You have open access to both ends of the tube.

Choose a pull-through purge kit when:

You’re welding installed pipework where you can only access one end.
You’re working on long pipe runs and want to minimise argon consumption.
The pipe has bends, elbows, or tees between your access point and the weld.
You’re moving from joint to joint along a single pipe run without removing and reinserting equipment.
You’re working with larger diameter pipes (6″ and above), where filling the full volume would burn through gas.

And sometimes, you might need both to address different problems. Plenty of welders and fabrication shops carry a tube purge plug kit for bench work and short runs, and a pull-through system for site work and installed pipework.

A Quick Word on Sealing the Rest of the Joint

Whichever purge kit you use, you’ll still need to seal around the weld joint itself to stop oxygen sneaking in from outside. High-temperature aluminium tape is the most common method, but for flanged connections and mechanical joints, industrial gaskets and industrial sealing solutions play a role in maintaining the integrity of the purged environment – particularly in high-spec process piping.

Get the Tools You Need with Industrial Experts

Neither kit is better than the other – they’re designed for different situations. A tube purge kit is hard to beat for speed and simplicity on small-diameter bench work. A pull-through system pays for itself in gas savings and flexibility the moment you’re on site, working with longer runs and installed pipe.

If you’re not sure which setup suits your application – or you need a kit built for a non-standard size – get in touch with Industrial Experts. We can walk you through the options and make sure you’re set up to purge efficiently, save gas, and produce clean welds every time.