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Adjustable spanner for plumbing

Updated: 22 October 2026

You are under the kitchen sink with a 15 mm copper pipe, or beside a radiator with a 22 mm valve tail, and the adjustable spanner will not seat on the nut. The pipe size is not the width across the flats. This page covers an adjustable spanner for plumbing on ordinary UK water joints: which openings in this set can pass a 22 mm compression nut, how to hold the fitting body, and where you stop for gas. It sits beside the main [adjustable spanner comparison](/hub/hand-tools/adjustable-spanner). The figures are printed on those amazon.co.uk listings, not a lab check of your nut. A qualifying purchase can earn us a commission at no extra cost to you. If the joint is on gas, put the spanner down.

You are under the kitchen sink with a 15 mm copper pipe, or beside a radiator with a 22 mm valve tail, and the adjustable spanner will not seat on the nut. The pipe size is not the width across the flats.

Our top picks

Stanley Stanley 200 mm adjustable wrench

Best overall

Stanley Stanley 200 mm adjustable wrench
8.4/10about £7.99
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Shall Shall 3-piece adjustable wrench set

Rank 2

Shall Shall 3-piece adjustable wrench set
6.5/10about £16.99
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WORKPRO WORKPRO 200 mm pipe-jaw wrench

Rank 3

WORKPRO WORKPRO 200 mm pipe-jaw wrench
5.7/10about £12.99
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On this page
  1. 1.The nut is wider than the pipe
  2. 2.Which of these jaws can reach
  3. 3.Two spanners, smooth faces
  4. 4.Where the spanner stops: gas

The nut is wider than the pipe

A 15 mm pipe and a 22 mm pipe name the tube, not the hexagon you turn. Faithfull's 15 mm and 22 mm open-ender, and Monument's 15/22 mm nut spanner, give 24 mm on 15 mm pipe and 32 mm on 22 mm pipe. BuildWiz puts a standard 200 mm adjustable around 24–27 mm and says that range will not cover a 32 mm nut, while a wide jaw around 38 mm will. Do not treat 38 mm as a fact about these listings. Bahco's 9031 is a different model, and this set does not print that opening. A jaw that stops at 19 mm or 24 mm never reaches a 22 mm compression nut near 32 mm across the flats.

Which of these jaws can reach

Navegando prints 6–19 mm. Both Stanley bullets stop at 24 mm. Neither figure passes a nut near 32 mm across the flats. Shall states 35 mm on the 10 inch, WORKPRO states 42 mm, and MAXPOWER's bullet states 40 mm. MAXPOWER's other field says 16 inches, so leave that listing unsettled. The wider order of checks is in the adjustable spanner buying guide.
Stanley Stanley 200 mm adjustable wrench

Testsieger

Stanley Stanley 200 mm adjustable wrench
8.4/10about £7.99
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Two spanners, smooth faces

A compression joint is a nut, an olive and a body. Turn only the nut and the body can twist. On a 15 mm or 22 mm water joint, use two spanners: one holds the body, the other turns the nut. BuildWiz describes that two-wrench method. How to reseat, and why a tube on the handle is the wrong extra force, is in how to use an adjustable spanner. Use a smooth jaw on chrome tap nuts and on brass. The WORKPRO prints 42 mm with a reversible toothed jaw, so it can pass a 32 mm nut and still mark a basin tap. If the head is too thick beside a basin waste, a thin spanner marked 24 mm and 32 mm is the access tool, and it is not one of these listings.

Where the spanner stops: gas

Shutting a stopcock on a cold-water pipe is ordinary householder work when you can reach the nut. A gas pipe, a meter, a flue or the case of a boiler is a different job. The Gas Safe Register limits householders to the user tasks in the appliance instructions. Regulation 3 of the Gas Safety (Installation and Use) Regulations 1998 requires competence for gas work, and Gas Safe registration where the work is done in the course of a business. Where a water nut is tight, soft or already rounded, a ring or open-ended spanner is kinder, which is the point of adjustable spanner vs combination spanner.

Common questions

What size is the nut on 15 mm and 22 mm compression joints?
Faithfull's 15 mm and 22 mm open-ender, and Monument's 15/22 mm nut spanner, state 24 mm across the flats for a 15 mm pipe nut and 32 mm for a 22 mm pipe nut. Those are seller figures, not a check of every radiator tail. Measure the flats you can see. A jaw that stops at 19 mm or 24 mm does not pass a nut near 32 mm.
Which listings in this set print an opening past about 32 mm?
Shall prints 35 mm on the 10 inch, WORKPRO prints 42 mm, and MAXPOWER's bullet prints 40 mm. Navegando stops at 19 mm and both Stanley bullets stop at 24 mm. Bahco and Amazon Basics print no millimetre opening. MAXPOWER also carries a 16 inch field that conflicts with the 40 mm bullet, so that listing is not settled.
Why did a 6 inch plumber spanner fail on a radiator collar?
A 22 mm radiator connection often carries a nut near 32 mm across the flats. A 6 inch adjustable that prints 19 mm, as Navegando does, never reaches those flats. Forcing it rounds the brass or chips the jaw, which is what one Navegando reviewer reported. Handle length is not the opening.
Do you need two spanners on one compression joint?
On a normal compression joint, one spanner holds the fitting body and the other turns the nut, so the olive does not twist on the pipe. The second tool can be another adjustable or a fixed spanner. Two spanners do not seal the joint. If the olive is pinched or the pipe end is scored, the joint can still weep.
Are serrated jaws right for chrome taps and brass nuts?
Not when the finish still matters. Serrated teeth mark chrome and brass, so use a smooth jaw on tap nuts and compression nuts. The WORKPRO prints 42 mm with a reversible toothed jaw, so it can pass a 32 mm nut and still be the wrong face for a chrome basin tap.
Can a householder use one of these on a gas fitting?
Not as a DIY job. Gas Safe Register guidance limits householders to the user tasks in the appliance instructions. Regulation 3 of the Gas Safety (Installation and Use) Regulations 1998 requires a competent person, and Gas Safe registration for work done in the course of a business. A jaw that opens to 42 mm does not change that.

Related pages

Best adjustable spanner

Adjustable spanner

Adjustable spanner size: opening before the length

How to use an adjustable spanner without rounding flats

Adjustable spanner vs combination spanner, when to switch

Sources

Public UK sources listed in the research digest for this comparison. Shelf prices and star lines are the amazon.co.uk figures in the product display.

  1. ISO 6787:2018, adjustable wrenches (retrieved 22 October 2026)
  2. BS ISO 6787:2018 (retrieved 22 October 2026)
  3. HSE: Provision and Use of Work Equipment Regulations (PUWER) (retrieved 22 October 2026)
  4. Gas Safety (Installation and Use) Regulations 1998, regulation 3 (retrieved 22 October 2026)
  5. Gas Safe Register: home improvements (retrieved 22 October 2026)
  6. Consumer Rights Act 2015, section 22 (retrieved 22 October 2026)
  7. Consumer Rights Act 2015, section 9 (retrieved 22 October 2026)
  8. BuildWiz: adjustable wrench (trade guide) (retrieved 22 October 2026)