Threaded and Grooved Pipe

Pipe Grade/Sched numbers

Categories of pipe based on their pressure ratings and applications.

Sched # is based on 1000 times the press/stress ratio

Ranges usually 10 to 160

Standard (STD)

Similar to schedule 40; rated for 150 psig, commonly used in residential applications.

Sizes 1/8 to 10”

Extra Strong (XS or XH)

Similar to schedule 80; rated for 200 psig, often used in steam and corrosion service.

Sizes 1/8 to 8”

Double Extra Strong (XXS or XXH)

No exact corresponding sched number; rated for 1000 psig, often used in hydraulic systems.

Pipe schedule number

Based on 1000 times the pressure/stress ratio, commonly ranges from schedule 10 to schedule 160.

Steel Grade A

Low carbon content; used for cold bending due to less brittleness.

Steel Grade B

Higher carbon content; offers more tensile strength than A.

Nominal ID

Size refers to the nominal internal diameter of steel/iron pipe at schedule 40, up to 12 inches. At sizes 14”+, the sizing becomes by exact OD.

Wall thickness calculation

Calculated as OD - ID / 2, where OD is outer diameter and ID is inner diameter.

If wall thickness changes, the ___ changes. ___ remains the same so standard threading equipment can be used.

ID changes with wall thickness, OD stays the same.

Typical pipe lengths you can buy?

usually 21’, +- 1/2”

Smallest typical size you can buy for steel/iron pipe?

Usually 1/8” and upwards

Pipe lengths supplied

Usually supplied in lengths of 21 feet with a tolerance of ± 1/2 inch.

Black iron finish

Cleaned, finished end, and treated with protective lacquer for corrosion resistance.

Pickled and Oiled finish

cleaned thoroughly of rust, grease, paint. Mild acid bath dunk and then oiled to prevent corrosion during transportation.

Yellow Jacketed Finish

PVC coating on outside

Galvanized pipe (also standard vs bending quality)

Standard: Bathes in molten zinc; has 2 oz per square foot zinc deposits only on the surface.

Bending Quality: galvanizing is treated specially to prevent flaking when bending. Zinc has low melting point so do not heat when bending.

Pipe abbreviations:

CWP

G

O

S

SP

WOG

WSP

1. Cold Working Pressure

2. Gas

3. Oil

4. Steam

5. Steam Pressure

6. Water Oil Gas

7. Working Steam Pressure

Close nipple vs space nipple

Space nipples have actual wall thickness integrity. Close nipples not allowed on gas.

4 Union types

1. Iron to iron

2. Iron body with bronze seat (Dart)

3. 1 Brass and 1 Iron Seat (Rex)

4. Gasket between 2 seating faces (Lip)

Malleable Iron

Cast iron heat treated to reduce brittleness, often shaped by hammering.

Malleable Fittings Classes (black or galvanized.

Class 150 (Standard):

-300 psig at 150F, if steam 150psig.

-1/8 to 6”

Class 300 (Extra Heavy):

-Steam service - 300psig at 550F.

-¼ to 3”

Pressure Cast Iron Fittings Classes (Black or Galvanized)

1. Class 125 (standard)

   • 1/4 “ to 8”

   • Max saturated steam press is 125 psig.

   • Liquid and gases 175 psig at 150F

2. Class 250 (Extra Heavy)

   1. high temps and pressures

   2. 1/4” to 8”

   3. Max steam pressure 250psig

   4. 400 psig at 150F for liquids and gases

Forged Steel Fittings Classes

1. Class 2000

   • Used with sched 80 pipe.

   • 2000 psig at 100F, steam is 615 psig.

2. Class 3000

   • Used with sched 160 pipe

   • 3000 psig at 100F, steam is 925 psig.

3. Class 6000

   • Use with XXS pipe

   • 6000 psig at 100F, 1855 psig steam psig.

NPS

Nominal Pipe Size; a standard for size measurement of pipes.

NPT

Nominal Pipe Thread; type of thread that enlarges at 3/4” per foot.

Joint compounds (pipe dope, teflon)

Primarily act as lubricants, rather than sealants, in pipe joints.

Pitch on pipe thread

Spacing between the crests of threads, measured across the diameter.

Max pressure rating of a fitting ____ as system temp increases

Max pressure rating decreases

What code is B31 for?

Pressure systems over 15psig, or hot water generated >160 psig and >250F.

Throw

Reference line to the face of fitting, typically the centerline of the fitting.

Thread engagement

Amount of pipe that enters into a fitting; crucial for proper fitting connection.

Fitting Allowance

Throw - Thread Enagement = Fitting Allowance. Think of it as the dead space between pipe and center of fitting

Grooved piping

Has no thread engagement; treated similarly to butt weld joints. Needs a shoulder of approx 5/8”

What is another name for a Grooved and Shoulder joint? Which mfg usually produces these?

Another name is “Vicking”.

Victaulic usually produces these.

MegaPress joint - pressure and temp range

-14 to 200 psig

-40 to 284F.

As Iron is purified, carbon is _____. Making it less brittle and more ductile but less hard wearing.

carbon is reduced.

Non ferrous is usually more resistant to ____ and ___.

corrosion and magnetism

Mild carbon steel, wrought iron, cast iron - Ferrous or non ferrous?

Ferrous

Aluminum, copper, brass, lead, plastic, concrete, wood - Ferrous or non ferrous?

Non Ferrous

What is the taper and thread angle required by NPT?

3/4” per foot of thread measured across diameter. Threads are cut at 30 degree angles for a thread degree of 60.

Taper can also be stated as 1” of 32” of thread measures on the radius, or 1” in 16” of thread on the pipe diameter. (In place of 3/4” per foot).

Oxygen process lines after threading, what must you do to ensure no explosion or contaminants?

Cleaned with carbon tetrachloride as oxygen and combustible lubricating fluid can cause explosions.

4 most common dimensions for piping?

Center to center

Center to end

End to End

End to End overall

Swarf

Oily shavings from threading

When do you stop threading using a hand threader?

When outer faces of dies are flush with 1 end of the pipe or when sizing plate reaches dropout point on tool housing. Once done threading, you turn CCW to back off the threader to be able to remove it.

Hand threading technique

Use a pumping action and body weight, ensuring to remove swarf after cutting.

Pre-oil for threading

Applying oil before starting to thread to reduce friction and heat.

Cutting fluid purpose

Keeps tool cool, lubricates the cut, produces better finishes, and clears swarf.

Mineral fatty oil

Common cutting oil type for non-ferrous metals and light mild steel.

Often used for Copper

Extreme Pressure oils (EP)

Have added sulphur and chlorine compounds; used for high pressure cutting.

Brass fitting threading lubricant oil

Soapy water

Steel or wrought iron threading lubricant oil

thread cutting oil

Soluble cutting fluid

Mixed with water; used when cooling is highly important during cutting.

Stainless steel cutting fluid

Requires special high sulphur oil for effective machining.

Allowed cutting fluid temperatures

Should not exceed 43°C during the threading or cutting process.

Galvanized (bending quality)

Specially treated to prevent flaking when bending.

Fitting allowance

Subtracting thread engagement from the throw to determine usable fitting space.
F.A = Throw - Thread Engagement

Pitch definition

The distance from one peak of the thread to the next peak.

Cut groove advantages

Requires a thicker pipe wall; no restriction at groove helps reduce pressure loss. Min sched 40.

Roll groove definition

Uses thinner wall diameter and is acceptable for schedule 10 pipes. May cause pressure loss or turbulent flow in line it deforms the pipe

Press connect joints

Utilizes a sealing element and grip ring to connect pipes; often used in steel.

Ductile Iron

Most common material for fittings, known for good strength and ductility.

Pig iron

First known form of purified iron, high in carbon.

Non-Ferrous Pipe

Usually more resistant to corrosion and magnetism; includes materials like aluminum and copper.

What angle ti cut threads?

30 degrees, it makes angle at 60 degrees

Cut and roll groove- size ¾ to 6” how much engagement material needed for clamps?

5/8” shoulder from face to shoulder

Grade E gaskets max service temp

230F or 110C

Victaulic different clamp types (3)

Deflection

Regular seal

Expansion clamps

How does victaulic clamps seal?

Using system pressure, may leak beforehand until system up to pressure

Gas Vapor lines at pressures over 125 psig should be ___ unless welded

XS grade

Steel and iron pipe is sized by ID up to and including ___, and ___ and over is by OD.

Up to 12” is ID, 14” and over is OD.

List 5 pipe end finishes available

1. Plain

2. Thread

3. Thread and Coupled

4. Beveled

5. Grooved

Best safeguard against poor threads, heat and excessive die wear?

Generous bath cutting oil

When would you use a universal die head?

Ridgid 300 or 535

To make custom nipples for threading you use?

Nipple Chucks

What are 5 things a cutting fluid does?

1. Keeps die cool

2. Keeps pipe cool

3. Lubricates

4. Good finish on work

5. Aids to clear away swarf

Which cutting fluid stains copper and its alloys?

Sulphured oils

High viscosity in cutting oil means?

less cooling and penetrating power

Which oil to use if cooling is most important?

Petroleum oil capable of forming an emulsion with water (Soluble Cutting Fluid)

Cut vs Roll groove - which one requires thicker minimum piping walls?

Cut groove

Does water deteriorate elastometer gaskets?

No

How are gaskets identified to show which fluids they can handle?

Marked with a stripe

2 Ways to control thermal expansion?

1. Expansion loop

2. Expansion joint

Main usage of a flex joint?

Isolate vibrations from equipment such as pumps

How do you describe a bull head tee?

Bull head tee: Branch is largest pipe size

Even if branch is largest, describe the runs first then branch last

Ex: 2×2×4

How would you identify a Tee (#by#by#)

Runs first (largest to smallest) then branch

Ex: 3×2×2

Common applications of steel pipe? (3)

1. Compressed air lines

2. Gas Lines from resi gas meters to furnace or appliances

3. Hot water supply and return

What is AWWA?

American Water Works Association. Recognizes the groove and shoulder system that is designed for potable water.

What is ASTM?

American Society for Testing and Materials

Where might you often see groove and shoulder systems?

-Paper and pulp

-Oil and gas

Since the gasket withstands the chemicals

Single wheel vs double wheel cutters - Adv and Disadv

Single Wheel:

Adv - Small Burrs, only inside burr, easy tracking Disadv - needs full 360 to turn

Double Wheel:

Adv - useful in small spaces, Disadv - Makes large burrs on inside and outside of pipe, tendency to spiral.

What does threading compound mainly do?

Lubricates the threaded joint.

When is a mineral fatty oil best used?

-Non ferrous metals, when high finish precision work i needed.

What does the schedule of a pipe designate?

Pressure / Stress Ratio X 1000

List 3 types of alloyed steel pipe

1. Stainless

2. Chrome/Moly

3. Copper alloys

List 6 common surface finishes before delivery:

1. Lacqured

2. Pickled and Oiled

3. Galvanized

4. Painted

5. Asphalt/Bitumen

6. Yellow Jacketed

Tightening a fitting onto pipe, hand turn ___ to ___ and wrench ___ to ___

Hand turn 4 to 6.75, wrench 2 to 3.

Difference between coupling and thread protector?

Coupling - Tapered threads

Thread protector - Parallel threads

Which reamer is for hand thread only, and which can be used with power vise and hand thread?

Spiral Flute Reamer is hand only.

Straight flute reamer can be used on both.

What do fittings do?

Add branches or change in direction to a system.