Frequently Asked Questions


Who is the contact person for Fittings?

Craig Schapiro
1 800 999 2550 x 1238

What is the difference between C153 and C110 fittings? Can one be substituted for the other?

The difference between a C153 and C110 fitting is primarily the wall and flange thickness. All other critical dimensions are the same. The rated pressure for C153 and C110 fittings is the same. The two fittings can generally be substituted for each other based on specification.

Are all SIGMA fittings hydrostatically tested?

All fittings are hydrostatically tested at 1 ½ times the rated pressure before they are shipped from the foundry.

What is the heat code and what does it represent?

The heat code is an 8-10 digit code cast on all SIGMA fittings to trace the material used to fabricate each fitting. The heat code provides the foundry code, year, month, date, furnace and ladle number.

Do all fittings have an acceptable standard deflection?

Depending on the size and type of joint used, allowable deflection varies from 2 to 5 degrees.

What are the standard linings and coatings for SIGMA fittings?

In accordance with ANSI/AWWA C104, cement mortar is the standard lining for SIGMA fittings.

Mechanical Joint and Push-On Fittings are cement lined and coated inside and outside with NSF 61 approved asphalt paint.

Flange Fittings are coated with red shop coat primer on the outside, cement lined, and coated with and NSF 61 approved asphalt paint inside.


Can SIGMA change the standard lining/coating in a fitting to meet specifications?

Yes, if the specification allows for application on a previously coated fitting.  In those cases, the cement and asphalt can be sandblasted to remove the lining and/or existing paint and the required material can be applied.

Is there a procedure for repairing damaged cement linings in the field?

Yes. As per ANSI/AWWA C104/A21.4:

” Defective or damaged areas of lining may be patched by first cutting out the defective or damaged lining to the metal so that the edges of the lining not removed are perpendicular to the pipe wall or slightly undercut. A stiff mortar is then prepared, containing not less than one part of cement to two parts of sand, by volume. This mortar is applied to the cutout area and troweled smooth with adjoining lining. To provide for proper curing of patches by preventing too rapid of a moisture loss from the mortar, the patched area is normally seal-coated immediately after any surface water evaporates, or alternatively the area is kept moist (e.g. with wet rags over the area or with the ends of the fitting taped over with plastic film, etc.). Of course, in potable water-related applications, no patch or curing components should be used in the repair that would negatively affect health or water quality.”

Do fittings require a boss to be tapped?

It depends on the tap size and wall thickness of the fitting; a boss is
recommended, although it is not always required.

Please contact SIGMA for specifics.  Click here

What size taps can be provided? Do these taps have to be ordered from overseas or are they sourced at SIGMA warehouses?

The standard tap size is 2”.  However, SIGMA can manufacture customized taps in a wide range of sizes according to specifications.  Some taps are sourced at SIGMA warehouses; others are procured from overseas.

Please contact Customer Service for information. Click here


Who is the contact person for Accessories?

Craig Schapiro
1 800 999 2550 x 1238

What are SIGMA’s packaging capabilities for bolt and gasket packs?

SIGMA can supply Flanged Gasket and Bolt Packs and Mechanical Joint Gasket and Bolt Packs.   These packs can be customized as required.

Can SIGMA provide private label boxes for customers?

Yes, please contact SIGMA for the procedure. Click here

What are the different types of gasket materials SIGMA offers?

  1. SBR
  2. EPDM
  3. Neoprene
  4. Nitrile

For information on specific applications, as well as SIGMA seal and transition gaskets, please contact SIGMA.  Click here


What is SIGMA’s product and size range in nuts & bolts?

  • T-head Nuts and Bolts: 5/8” x 2 ½“ through 1½“ x 8”
  • Hex head Nuts and Bolts:  5/8” through 1½”.

Nuts and bolts are offered in a variety of materials ranging from low-steel alloy to stainless steel.

Can SIGMA provide domestic nuts and bolts? If so, what types?

Yes, SIGMA can provide all types of T-head and Hex head nuts and bolts from domestic sources. 

What is the difference between 304 and 316 stainless steel?

304 stainless steel contains 18% chromium and 8% nickel while 316 stainless steel contains 16% chromium, 10% nickel and 2% molybdenum. Added molybdenum for 316 stainless steel provides better corrosion resistance to chlorides such as seawater and de-icing salts.

What lengths and materials are available in threaded rod?

SIGMA offers threaded rod in a variety of diameters and lengths. It can be cut to any sized required according to customer specifications. Threaded rod is available in black carbon, zinc plated, and stainless steel.


Who is the SIGMA contact person for Restrained Joint Devices?

Steve McDonald

What different types of pipe restraint applications does SIGMA offer?

SIGMA offers the following restraint applications for ductile iron pipe:

  • Import wedge restraint for mechanical joint fittings (SLDE)
  • Domestic wedge restraint for mechanical joint fittings (D-SLDE)
  • Split wedge restraint for existing mechanical joint fittings (SSLD)
  • Modified wedge restraint for oversize pipes (SLDM)
  • Wedge restraint pipe bell harness (SLDEH)
  • Split wedge restraint pipe bell harness (SSLDH)
  • Serration-style restraint for push-on/trim tyton fitting

SIGMA offers the following restraint applications for AWWA C900, C905, C909 and ASTM D2241 IPS PVC pipe:

  • Import wedge restraint for mechanical joint fittings (SLCE)
  • Domestic wedge restraint for mechanical joint fittings (D-SLCE)
  • Wedge restraint pipe bell harness (SLCEH)
  • Serration-lock restraint for mechanical joint and push-on fittings (PWM)
  • Serration-lock restraint for pipe bell harness (PWP)
  • Serration-lock and split gland restraint for pipe bell harness (PWH)
  • Serration-lock and split gland restraint for pvc pressure fitting (PWPF)
  • Serration-lock restraint for mechanical joint fitting to IPS pvc pipe (PVM)
  • Serration-lock restraint for IPS pvc pipe bell harness (PVP)
  • Serration-lock restraint for IPS pvc pressure fitting and IPS pipe (PVPF)

In addition, SIGMA offers SIGMAFlange adaptor sleeves for restraining plain-end ductile iron, PVC and IPS PVC pipes to a flanged outlet, wedge and serration-lock restraint for high density polyethylene (HDPE) pipes, set screw Zip Flanges for securing plain-end ductile iron or steel pipes to a flanged outlet and set screw retainer glands for the restraint of ductile iron pipe to mechanical joint fittings.

What are key design features/benefits in SIGMA’s One-Lok wedge action restraint?

A gripping action that increases with pressure changes due to surges and water hammers common in pipelines.

The break-off top actuating bolts undergo a 100% quality control program using an initial machining stage to ensure precise torque fracture.

Break-off top bolts can be easily replaced during repairs and maintenance.

The wedge inserts move in only one direction (towards the outer pipe wall surface), eliminating the chance of reversed movement away from the pipe wall if tightened in the wrong direction.

Do SIGMA restrainers provide individual heat codes?

Yes.  All SIGMA restraining devices including componentry (wedge inserts and break-off top actuating bolts) offer a heat code to ensure the integrity of the ductile iron material.

Why are the wedge segments in the One-Lok restraining gland for ductile iron pipe heat-treated?

The wedge inserts used with the One-Lok restraining gland for ductile iron pipe are heat treated to a minimum brinell hardness of 370 which allows the wedge’s frontal tooth to engage the pipe wall for maximum restraint capabilities.

What is the proper torque pressure for tightening the T-head nuts and bolts on the One-Lok wedge-action restraining glands?

Proper torque for T-head nuts and bolts varies with the nominal size of the restrainer/fitting assembly as outlined below per AWWA C111 latest edition.

  • 3” – 45 to 65 ft. lbs
  • 4”-24” – 75 to 90 ft. lbs
  • 30” & 36” – 100 to 120 ft. lbs
  • 42” & 48 – 120 to 150 ft. lbs

Can PV-Lok serrated clamps be used to restrain PVC pipe inside a steel casing?

PV-Loks serrated clamping rings can be used to restrain PVC pipe inside of steel casing. The casing pipe must be selected to accommodate the maximum outside diameter of the restraining clamp and some form of casing spacer to prevent the restrainer ring from sliding along the steel casing pipe and ensuring the carrier pipe is properly centered.

Municipal Construction Castings

Who is the contact person for Municipal Constructions Castings?

Charlie Kyle
317 850 0359

Where can MCC drawings be found?

Many common drawings are available through Customer Service. Contact Greg Fox at or 800-824-4513 ext 4213.  In addition, SIGMA’s Engineering Division maintains a complete database of all MCC drawings. Contact the Engineering Division at


What is H20 loading for castings?

Based on guidelines provided by the AASHTO (American Association of Highway Transportation Officials), the designation H followed by a number indicates the type of load (e.g. the weight of a truck in tons) that the casting is required to bear.

If the casting is H20 load-rated it means that the casting will withstand at a minimum 0.4 times a gross vehicle weight of 40,000 lbs, or an equivalent of 16,000 lbs direct load, and is suitable for highway traffic loads.

Can SIGMA make castings from both ductile iron and cast iron?


Are there different grades of iron for castings? What are they?

Yes, ductile iron and cast iron.

Ductile iron has different grades such as 60-42-10, 65-45-12, 70-50-05.

Cast iron has different grades such as Class 20, Class 30, Class 35.

Can SIGMA fabricate steel frames and grates?



Who is the contact person for E-products?

Greg Fox
256 496 3388

What is SIGMA’s range for Polywrap

Polywrap is available for all ductile iron pipe in sizes 3-64”.


What is the difference between 8 mil Polywrap and 4 mil cross-laminated Polywrap?

Eight mil is the original product chosen to protect ductile iron pipe and fittings from corrosion.  It is made from virgin resin and is a single layer film. 

Four mil is an engineered multiple layer film made of high density polyethylene that is cross-laminated in a bidirectional sheet to give it superior tear and puncture resistant properties.

Is Polywrap available in colors?

Polywrap is available in stock colors and sizes, and SIGMA can produce special runs with a minimum order of 3500 pounds.

Does SIGMA sell the tape forPolywrap?

Yes; SIGMA offers 10 mil tape in 1 ½ ” or 2” width on 100’ rolls.

What is the difference in Slow, Standard and Hot Mix hydraulic cement?

The only difference in the three types of cement is the time required for it to set. 

  1. Slow Set:  approximately 20 minutes.
  2. Standard Set:  approximately 3-5 minutes.
  3. Hot Set: approximately 45-90 seconds.

What is SIGMA’s range in copper tubing?

SIGMA supplies Type K, Type L, as well as other less common types of copper tubing.  SIGMA’s copper tubing line spans a wide range of diameters and is available in both coil and straight varieties.

What is a companion flange used for?

Companion flanges are used to convert plain-end steel pipe into flanged
pipe. Click here for more information.

Treatment Plant Division

Who is the contact person for a Plant Work quote?

Kelly Grant
800 999 2550 x 1269

Who is the contact for Plant jobs?

Dave Pietryga
586 703 6577

Ingrid Sondag
602 320 8522

What special linings and coatings does SIGMA offer?

Exterior Coatings:
• Bare Uncoated
• Standard Asphaltic Coating
• Tnemec 37H-77 Alkyd-Phenolic Primer (Red)
• Tnemec 140-1211 Epoxy (Red)
• Tnemec 46H-413 Coal Tar Epoxy (Black)
• Tnemec 66 Boston Gray (Gray)
• Fusion Bonded Epoxy (Red)
• Wasser Ferro-Clad Primer (Blue or Gray)

Interior Linings
• Bare Unlined
• Double Cement Lined with Seal Coat
• Induron PROTECTO 401 [REGISTERED] Ceramic Epoxy
• Fusion Bonded Epoxy


What are HYDROTEC channels made of?

HYDROTEC channels are made of fiber reinforced concrete, which is sturdier than polymer concrete channels.  This more durable material drastically reduces breakage during transportation and installation. Additionally, Hydrotec trench drains are made of the same material as the concrete bedding that surrounds them, which means that they respond to environmental and temperature changes in the same way.  This reduces the risk of cracking and breakage due to fluctuations in heat, cold and moisture.

What is the size range of HYDROTEC Trench Drains?

Length:  HYDROTEC trench drains are available in 39.37” (1 meter) and 19.69” (0.5 meter) lengths.

Width:  HYDROTEC trench drains are available in 4”, 6”, 8” and 12” widths (throat or reveal width).

What is HYDROTEC Trench Drains country of origin?

HYDROTEC trench drains come from Germany.

Are HYDROTEC Trench Drains pre-sloped?

The 4” and 6” trench drains are available both flat and pre-sloped. The 8” and 12” trench drains are only available flat.

Are HYDROTEC Trench Drains available in different depths?

Yes, please consult our catalog for further details.   Click here

Are Hydrotec grates available in different materials and load classes?

Yes.  Grates are available in Galvanized Steel (Load Classes A, B and C) and in Ductile Iron (Load Classes C, D, E and F).

Are ADA grates available?

Yes, ADA grates are available in Galvanized Steel and Ductile Iron. Please consult our catalog for further details.  Click here

Are High Heel grates available?

Yes, High Heel grates are available for the MAXI 100 both in Galvanized Steel and in Ductile Iron.

How do HYDROTEC Trench Drains connect to each other?

HYDROTEC trench drains come with a male/female built in profile so they can be easily connected.

What is the HYDROTEC Trench Drain installation process?

HYDROTEC trench drains are easy and quick to install.  The trench drains do not need to be hung or suspended, they are simply placed in a stable base and concrete is poured around them. This process, along with HYDROTEC patented locking mechanism, significantly reduces the time spent by the crew completing the job.

Do HYDROTEC Trench Drains require a concrete encasement?

All MINI, TOP and MAXI trench drains require a concrete encasement. Please refer to our Installation Instructions for further details.  Click here

Are HYDROTEC Trench Drains liquid tight?

Yes, HYDROTEC fiber reinforced concrete channels are liquid tight to EN 1433 standard.

Can we install HYDROTEC Trench Drains at an angle? How about on a curve?

A 45 degree angle can be created by using one of the special channels that come with an exit on the side. HYDROTEC fiber reinforced concrete  channels and galvanized steel or ductile iron grates can be cut onsite to create any angle necessary.

HYDROTEC Trench Drains can be installed in a curve. Please refer to the catalog for further details. Click here

Are Catch Basins available?

Yes, Catch Basins are available for all HYDROTEC Trench Drains

Piping Products

How much do I need to spend on SPP products in order to get prepaid freight?

In the continental USA, you need to place an order for $1500.  If you are ordering from outside of the continental USA, please contact your sales representative. Click here.

Do you have an order minimum for SPP products?

No. You can place any size of order, according to your requirements.

How many turns should it take to turn a valve on with your indicators?

The number of turns depends on the type of gate valve being used.  Please contact the sales
department for specific details. Click here.

Are your domestic nipples made from coated pipe?

Yes, we use industry standard coated pipe on all our domestic nipples.

Can you explain the difference between the SIGMA SigLet and the SIGMA UniLet products?

The SigLet is a domestic product whereas the UniLet is an import.  There are engineering differences between these two products that will give you more options when using automatic welders.  For further information, see this product information.  Click here.

Are your malleable fittings made in China?

No. These fitting are from Indonesia.

What is the biggest difference between Cast Iron and Ductile Iron?

These two irons possess different metallurgical properties.   Ductile iron is slightly softer, for example.  Products made from these materials will thread differently on to pipes and fittings.

Are your malleable fittings U.L. & F.M. approved?

Sigma’s malleable iron fittings are U.L. approved, as per the industry standard.

Will your post indicator valve work with all upright indicator posts?

Yes these valves will work with most upright indicator posts, dependent on the installation.  We suggest that you confirm this directly with your sales representative, who can clarify your specific installation. Click here.

Do your butterfly valves have approval from the California State Fire Marshall?

We are in the approval process currently and expect approval mid 2014.

Are your grooved outlets import or domestic?

Currently, SIGMA offers a domestic grooved outlet in schedule 10 roll grooved or schedule 40 cut

Does SIGMA offer any ductile iron fittings in a 3/4″ size?

No, not at this time.