Flanged cast iron hydrant extension, drawing from the SIGMA CHX spec sheet

Drawings from the CHX spec sheet (October 2026), which shows a plain spool with no break-off groove. The item number sets the type, drilling, lining and size.

Item # CHX612-6 Questions and answers (6)

Hydrant Extensions

6 in. cast iron fire hydrant extensions, 4 to 36 in. tall. Replacing one? Match the type, drilling, lining and height, flange face to flange face.

View price list (PDF)

Break-off: grooved to break if a vehicle hits the hydrant
Solid and break-off; double break-off with San Diego drilling
250 psi on the CHX spec sheet (plain spool)
See all specifications

Type: Solid

Drilling: Los Angeles 6-hole

Size: 6 x 12 in.

Made: Ask your regional team

Lining and coating: Cement lined, asphaltic coat

Cement lined, black inside and out, per the price list (ANSI/AWWA C104 on the spec sheet).

Your distributor

SIGMA sells through waterworks distributors. Order with item # CHX612-6.

Quote from SIGMA

Job location

Sends your quote list to the right regional team.

Quantity

Download the CHX spec sheet

Need help on the job?

Call the Western regional team in Ontario, CA, at 800.688.6230 with the size, type and drilling you need.

Hydrant buries Spec sheet

Everything about this extension: 6 x 12 in.

Details, specs, every size and the questions buyers ask. Open what you need.

Product detailsWhat it is, highlights and documents

About hydrant extensions

A hydrant extension is the flanged spool that brings the line from the bury up to grade under a wet-barrel fire hydrant. SIGMA's 6 in. cast iron extensions come 4 to 36 in. tall, solid or break-off, flange by flange, cement lined or fusion bonded epoxy.

The CHX spec sheet shows a plain spool with no break-off groove: cast iron to ASTM A48 Class 30, rated 250 psi, conforming to AWWA C503-18 and NSF 61 certified. Break-off extensions are not on the spec sheet.

Highlights

Solid or break-off
Los Angeles, San Diego and 8-hole drilling

Documents

SpecificationsSolid, 6 x 12 in.

Solid, 6 x 12 in.

Item number	CHX612-6
Extension	Solid, Los Angeles 6-hole
Size	6 x 12 in.
Made	Ask your regional team
Lining and coating	Cement lined, asphaltic coat
Pressure rating	250 psi
Max. deflection
Weight	Ask your regional team
Pallet quantity
Spec sheet	CHX
Price list	Hydrant Bury and Extensions (Cement Lined), effective 3/24/25

Materials and build

Material	Cast iron, ASTM A48, Class 30, per the CHX spec sheet
Ends	Flange by flange
Lining	Cement-mortar lining per ANSI/AWWA C104/A21.4, or fusion bonded epoxy
Outside	Asphaltic seal coat per ANSI/AWWA C104/A21.4, or fusion bonded epoxy per ANSI/AWWA C116/A21.16. San Diego drilled extensions: ask your regional team about the outside coating
Drilling	Los Angeles 6-hole: 3/4 in. holes on a 9.38 in. bolt circle. 8-hole: 7/8 in. holes on a 9.5 in. bolt circle. San Diego 6-hole: 7/8 in. holes on a 9.5 in. bolt circle. 6-hole x 8-hole as the price list names it. Other drilling: ask your regional team

Rating and use

Pressure	250 psi on the CHX spec sheet, which shows a plain spool (no break-off groove)
Standards	Plain spool on the CHX spec sheet: conforms to AWWA C503-18 and NSF 61 certified. Break-off extensions: ask your regional team
Break-off	Not shown on the CHX spec sheet. Ask your regional team for a drawing

Dimensions

Size	Printed as 6 x height. The height runs from flange face to flange face (H on the CHX spec sheet). Match it to the plans
Other dimensions	Ask your regional team

From the hydrant price lists (cement lined and fusion epoxy, effective 3/24/25) and the CHX spec sheet (October 2026).

Every size and item number16 sizes · item numbers

The sizes that come with the type, drilling and lining picked above. Pick a size to load it.

Hydrant extensions: item numbers by size
Size	Item #	Pressure
	CHX604-6	250 psi
	CHX606-6	250 psi
	CHX608-6	250 psi
	CHX610-6	250 psi
	CHX612-6	250 psi
	CHX614-6	250 psi
	CHX616-6	250 psi
	CHX618-6	250 psi
	CHX620-6	250 psi
	CHX622-6	250 psi
	CHX624-6	250 psi
	CHX626-6	250 psi
	CHX628-6	250 psi
	CHX630-6	250 psi
	CHX632-6	250 psi
	CHX636-6	250 psi

Item numbers from the hydrant price lists, effective 3/24/25. Fusion bonded epoxy extensions are listed to 32 in. San Diego drilled extensions are listed cement lined only; for fusion bonded epoxy or a C210 exterior with San Diego drilling, ask your regional team.

Questions and answers6 questions buyers ask about hydrant extensions

Where do I find the price?

On SIGMA's price lists. Where an item is on a posted list, the View price list button near the top of this page opens it, and every posted list is on the Price Lists page. SIGMA sells through waterworks distributors, and your distributor sets your price. For contract pricing, ask your regional team.

What does a hydrant extension do?

It is the flanged spool, also called a hydrant riser or hydrant spool, that brings the line from the bury up to grade under a wet-barrel fire hydrant. Crews often add one in the field to meet the finished grade.

Solid or break-off?

A break-off extension has a groove made to let it break if a vehicle hits the hydrant, and it usually sits at grade. A solid extension has no groove. Check the plans or the local standard. The price list also names double break-off extensions for San Diego drilling: ask your regional team what they include.

Which drilling do I need?

The one on your plans or the local standard. The price list has Los Angeles 6-hole, 8-hole, 6-hole x 8-hole and San Diego drilling on most heights. For other drilling, ask your regional team.

How tall do they come?

4 to 32 in. in 2 in. steps, plus 36 in. On the CHX spec sheet, the height H runs from flange face to flange face. Fusion bonded epoxy extensions are listed to 32 in.

Cement lined or fusion bonded epoxy?

Both are on the price lists: cement lined, black inside and out, or fusion epoxy lined and coated. San Diego drilled extensions are listed cement lined only: for the outside coating, fusion bonded epoxy or a C210 exterior with San Diego drilling, ask your regional team.