Gate Valves

In addition to the year of manufacture, resilient wedge gate valves contain a six digit Julien number that represents the date and shift the bonnet was created. For example, if the code reads 071043, then 07 is the month, 10 is the day, 4 is the last digit of the year, and 3 is the shift.

The valve may be larger than shown on the plans. Continue to operate based on the next size valve. Alternatively, the valve may have a bevel or spur gear to assist during operation. Check the plans to see if it a gear was installed on the valve. Excessive torque may have been applied to the wrench nut at some point and damaged the stem or stem nut. If this is the case, expose the valve and inspect the stem and stem nut. Replace if necessary.

First, be sure the valve is completely closed by counting for a proper number of turns (based on the valve size). Verify the required closing torque by comparing to the manufactures published information. The disc may have been closed against debris. If this is the case, create flow through the valve (open a nearby downstream hydrant) and exercise the valve to loosen/remove the debris. Also, air may be trapped in the line. Flush the line to remove the trapped air. Add an air release valve if necessary.

Tuberculation or debris may have built up in the seat area, particularly with double disc gate valves. To correct, create flow through the valve (open a nearby downstream hydrant) and then exercise the valve to loosen/remove the debris.

The valve box may be interfering with the wrench nut socket/tool. Look down the valve box to see if it is too close to the wrench nut. Reposition if necessary. Alternatively, the stuffing box bolts and nuts may have been tightened down unevenly during assembly. If that is the case, loosen and retighten stuffing box bolts and nuts evenly. In addition, debris or corrosion may have built up between the stem and stuffing box due to lack of operation or gritty backfill. This requires removal of the stuffing box (stem if needed) and cleaning and/or replacement of the stem and stuffing box. Lastly, debris could have wedged under the disc. Expose the valve. Isolate the valve from flow and relieve pressure. Remove the bonnet. Clean out the debris.

Verify the bolts and nuts are torqued according to the operating manual. The bonnet gasket O-ring may be damaged or pinched. Isolate the valve from flow and relieve pressure. Remove the bonnet. Replace the gasket. Alternatively, the body or bonnet flange may be cracked or broken. Inspect the valve body and bonnet flanges. Replace damaged items.

It is possible that the stuffing box packing is not sealing properly. If this is the case, remove the stuffing box and replace the stem O-rings and the stuffing box packing. Note that U.S. Pipe Valve & Hydrant started using O-rings in 1952.

The AWWA operating formula for opening/closing a gate valve is 3 times the nominal valve size plus 2 or 3 turns of the operating nut. For example, a 6-inch gate valve would require 6 x 3 = 18 turns plus 2 or 3 turns, for a total of 20 to 21 turns.

Contact our customer service for further information. (This will be very limited, which may be only “O” rings.)

No, parts are no longer available for this product.



Mueller Co. offers two (2) different types of classes: (1) Mobile Training Van; and (2) Annual Training School. The Mobile Training Van takes our school on the road in the Spring, Summer and Fall with stops at U.S. Pipe Valve & Hydrant Stocking Distributor locations. The van covers a different area of the continental US each year. There is no charge to attend one of these sessions. Contact your local U.S. Pipe Valve & Hydrant Authorized Distributor to inquire about classes in your area, and to register your interest in attending. Our Annual Training School is conducted every winter at the Mueller Technology Center in Chattanooga, TN. This 3-day class is designed specifically for distributor personnel. To assure each participant will receive proper hands-on product experience, the class size is limited to 20 students.


Fire Hydrants

Yes, please contact our customer service representative at 800-423-1323 for a complete listing. (Unless we want to have a diagram of the S on the website.)

Yes, please contact our customer service representative at 800-423-1323 for a complete listing. (Unless we want to have the diagrams listing of parts we offer.)

Start with the first hydrant nearest where the new main connects into the system, and work toward the farthest hydrant. Open the first hydrant as fast as possible until fully open, and allow it to run for five minutes, then close it fully. Do this on successive hydrants until the entire system of pipes has been flushed.

The first two numbers in the code are the number of threads per inch and the last three digits are the pitch diameter. For example, a 40560 thread gage is 6.0 threads per inch (TPI) with a 5.60" pitch diameter (PD).

For Sentinel® Fire Hydrants Only: Instead of using a standard MJ connection with an add-on bolted restraint system, which can leave several bolts out of reach underneath the pipe, use the Mueller® Aqua-Grip® system, which includes an MJ-type connection and pipe restraint without any bolts underneath the pipe. Plus, the Aqua-Grip systems involves far fewer bolts to tighten when it’s installed.

For Sentinel® Fire Hydrants Only: The Mueller® Vertical Aqua-Grip® Hydrant allows the use of any length of standard ductile iron pipe to be used to extend from the hydrant shoe directly down to the main’s level.

NFPA sets the guidelines which govern the spacing for private and recommended spacing for public water systems. Most engineers will follow the guidelines set forth by NFPA but with public systems they set their own rules and regulations. NFPA 1, Section says the maximum spacing for residential lots 20,000 square feet or larger should be 1,000 ft.; 750 feet for residential lots of less than 20,000 square feet; and 500 feet for townhomes and apartments. For more information, please visit:

This situation can occur if the hydrant has been left idle for many years without annual exercise, or if the main valve is brass and it is threaded directly into an iron mounting. U.S. Pipe Valve & Hydrant fire hydrants have brass-on-brass main valve mountings to help avoid corrosion that can occur with brass-on-iron. For a main valve assembly that cannot be loosened using a seat wrench, try pumping out all accumulated water, pour in one to two liters of a cola soft drink, and let it soak (overnight might be necessary).

U.S. Pipe Valve & Hydrant offers extension kits to increase bury depth for both M-94 and Sentinel hydrants. Contact customer service for kit numbers - specify change in bury depth needed. Shortening hydrant bury depth requires replacing the Lower Standpipe & Lower Rod.

Operating Nut size can be changed by simply replacing the Operating Nut with the required size. Generally hose and pumper cap nut match the operating nut so new caps may be required. Specify the thread gage and nut size when ordering.

Specify size of pumper nozzle and thread gauge and order the following: Nozzle Lock; Pumper Nozzle; Pumper Nozzle Gasket; Pumper Nozzle O-ring; Pumper Cap (Specify size and shape of operating nut.); Cap Chain w/Ring; Chain Hook(s)

Different coatings have been used over the years on USP hydrants. Since 2010 both M-94 and Sentinel hydrants have been top-coated with polyurethane epoxy. See the USP website for instruction on touch-up and repainting USP hydrants.

Many systems still specify the use of ground key valves in service lines, which are only rated to 100 psi. Testing new lists at 200 psi, even 150 psi push these valves to their limit and sometimes leakage can cause a test failure. Using Mueller 300® Ball Valves, which are rated at 300 psi can help assure successful testing. Mueller® Oriseal® Valves are plug style valves with O-ring seals, and are rated at 175 psi, and offer an alternative. When using ground key valves, it is helpful to rotate or “cycle” the key to redistribute the grease when installing the valve. Never tamper with the nut on the bottom of the key, as in Mueller valves, this nut is factory tightened to a precise torque, and loosening it can change the valve’s pressure holding capability.

First, make sure the hydrant is well lubricated; lubricate as directed in the operations manual. If lubrication isn’t the issue, it could be the hydrant has been over tightened and the stem bent. In this case, the stem will have to be replaced. If the hydrant is old or has not been exercised in sometime, corrosion or build up of deposits in the main valve could be a problem in which case, the main valve will have to be serviced. If it is an especially old hydrant, over fifty years old for instance, sometimes the best solution is to replace it.

The grease is designed to operate in both cold and warm climates. It is best to use USP grease. It is recommended that different greases not be mixed. Some greases are not compatible with others and can break down.

The rod coupling may be broken or the rod coupling pins were not installed or have failed.

Sentinel & M94 Maintenance Manuals &/or Videos

32: Lower Stem, 33: Lower Barrel, 29: Barrel Coupling Seal, A-38: Base O-Ring Seal

U1: Operating nut (specify size, shape, and opening direction), U8: Bonnet, U13: Revolving Nut, U24: Valve Rod Upper Section Assembly

Specify size of pumper nozzle and thread gauge and order the following: U-19: Nozzle Lock; U15: Pumper Nozzle; U16: Pumper Nozzle Gasket; U18: Pumper Nozzle O-ring; U17: Pumper Cap (Specify size and shape of operating nut.); U45: Cap Chain w/Ring; U46: Chain Hook(s)


Tapping Machines

Mueller no longer rebuilds the S tapping machines. Please contact John Pikciunas, authorized U.S. Pipe tapping machine repair shop at:, 423.364.8432.