Champion Big-Lock Straight Union Coupling - Standard and High Temperature (73mm to 220mm)

The grooved coupling is the whole idea of Champion Big-Lock. Two halves wrap a pair of grooved pipe ends, a gasket seals on the outside diameter, two bolts pull it together, and a 6 in aluminum main is joined in a couple of minutes by two people with a wrench. No welding, no flanges to line up, no threading, no hot work permit.

This listing is the straight union coupling that joins two lengths of Big-Lock tube in line, 73mm through 220mm, with a standard or high temperature seal.

Choose your size and seal from the dropdowns above.

Model Selection Chart

Champion catalogs a 273mm (10 in) Big-Lock range as well, but the current price list prints the 273mm couplings and most 273mm fittings as consult factory. Call or email and we will quote them.

How Many Couplings Does the Job Need?

More than people expect, and this is the line most commonly short on a take-off.

Every joint between two sticks of tube is one coupling. Big-Lock tube comes in 16 ft lengths, so a 200 ft main is roughly twelve couplings before you have added a single fitting. On top of that, the Big-Lock elbows, tees and reduction tees in this range are supplied with their couplings included, so those do not need separate ones, but the reducers are supplied without couplings and need two each.

Send us the layout and we will count them properly. Running out of couplings at hour six of an install is an expensive way to learn this.

Standard or High Temperature Seal?

The standard seal covers normal compressed air service and is what the overwhelming majority of systems use. The high temperature seal is for runs close to a compressor discharge or an aftercooler, hot plant environments, or where heat and lubricant carryover together are hard on the standard compound.

One honest caveat. Champion's current price list does not publish a temperature rating, a pressure rating or a dimensional table for the Big-Lock range, and we have not found a Big-Lock datasheet that does. We are not going to print numbers we cannot source. If your application is near a temperature or pressure limit, call us and we will get the figures from the factory before you order, which matters here because these are no-return items.

Shared Technical Specifications

Specification note. The price list publishes description, part number and list price for the Big-Lock range and nothing else: no pressure rating, no temperature band, no weights and no dimensions. Everything stated above comes from Champion's own published Big-Lock material. Ask us for anything further and we will source it from the factory rather than estimate it.

Ideal Applications

Plant mains and loop headers above 2-1/2 in, compressor room manifolds, replacing a corroded steel or black iron header without hot work in an operating building, and any run where the flow has outgrown Quick-Lock's 63mm top end. Common in large manufacturing, food and beverage, automotive assembly, and anywhere a shutdown to weld pipe is not acceptable.

Big-Lock and Quick-Lock Together

The normal architecture is a Big-Lock main loop with Quick-Lock branches. Big-Lock carries the volume around the building; Quick-Lock takes it from the loop down to the bays and the machines, where its push-fit fittings are far quicker to work with.

One warning worth repeating. 73mm Big-Lock and 63mm Quick-Lock are both called 2-1/2 in nominal and they are not interchangeable. Different outside diameters, different joint systems. Order by the metric size and the system name, never by the inch nominal alone.

• Big-Lock aluminum pipe, 73mm to 273mm
• Big-Lock 90 and 45 degree elbows and street elbows, supplied with couplings
• Big-Lock junction tees and reduction tees, supplied with couplings
• Big-Lock threaded adapters and reducers - note reducers need couplings ordered separately
• Big-Lock plug caps
• Quick-Lock aluminum pipe, 14mm to 63mm for the branches

Ordering Notes

• All Big-Lock products and accessories are NO CANCEL / NO RETURN. Champion states this in capitals at the top of every Big-Lock page. Confirm sizes and counts before the order goes in; we are happy to check the take-off with you first.
• Freight: all Big-Lock shipments are freight collect from Huntersville, NC 28078 or Las Vegas, NV 89113.
• Shipping weights: Champion publishes no weight for any Big-Lock fitting, so no catalog weight is carried on these variants. Large grooved couplings are heavy; we quote freight on the complete package.

Why Buy from Air Compressor Store

Air Compressor Store is an authorized Champion Pneumatic distributor. Big-Lock is a system you plan once and live with for twenty years, so send us the floor plan before you buy anything. Our compressed air engineers will size the main, decide where Big-Lock should hand over to Quick-Lock, count the couplings and fittings properly and quote the whole package at no charge.

Frequently Asked Questions

Do I need to groove the pipe myself?

Yes. Big-Lock tube is supplied plain-ended and the groove is rolled on site with the Champion manual grooving tool, which we also supply. That is what lets you cut a run to length in the building rather than ordering made-to-measure pipe. Budget for the tool on the first Big-Lock job; it is reusable forever after.

Is the coupling reusable?

The coupling hardware is, which is one of the real advantages of a grooved system over welding. Undo the bolts, pull the halves apart, move the pipe, reassemble. Inspect the gasket and replace it if it is nicked or hardened; replacement seals are catalogued separately in the Big-Lock range.

Why is the 220mm high temperature coupling so much more than the 168mm?

$1,467 against $482 at list, which is what Champion's August 2026 price list publishes. The high temperature seal premium grows sharply with size across the whole Big-Lock range. Both are shown here at Champion's list price rather than smoothed.

Can I join Big-Lock straight to steel pipe?

Not with this coupling, which is tube to tube. Use a Big-Lock threaded adapter to land on an NPT thread, or a Big-Lock flange kit to bolt to a flanged connection. Both are in the Big-Lock range and we can quote them with the couplings.

What pressure will Big-Lock hold?

Champion does not publish a pressure rating for the Big-Lock range in the current price list and we have not found one in a Big-Lock datasheet, so we will not quote you a figure. For comparison, Champion does publish 220 PSIG for Quick-Lock. If your system pressure is anywhere near the top of normal shop air, ask us and we will confirm with the factory in writing before you order.

Do elbows and tees come with couplings?

Yes, the Big-Lock elbows, junction tees and reduction tees are all catalogued with couplings included. The reducers are not and need two couplings each. That single difference accounts for most short orders on this range.