Module 1 : Pipes, Tubing, and Pipe Fittings

Question 1

What is piping?

Answer 1

Piping is a tubular section or hollow cylinder.

Question 2

What is the purpose of piping?

Answer 2

Piping is used to convey liquid from a tank to another tank, from a tank to machinery, from machinery overboard, etc.

Question 3

Where is piping used?

Answer 3

Piping is used extensively in a ship on machinery (i.e. propulsion), domestic systems (i.e. domestic fresh water) and HVAC (refrigeration and air conditioning).

Question 4

What materials are pipes made of?

Answer 4

• Carbon steel (iron & carbon alloy) pipe is the most commonly used
• Stainless
• Copper Nickel (Cuper Nickel or CuNi)
• Copper pipe for specific application
• Plastic

Question 5

Why is steel used?

Answer 5

• High pressure and temperature ratings
• Ease of joining
• Overall durability
• Cheap
• Easy to bend and work with

Question 6

For which systems is steel used?

Answer 6

• Steam
• Cooling
• Bilge and ballast
• Starting air systems
• Fire mains

Question 7

What are the two methods of manufacturing steel pipe?

Answer 7

• Seamed (welded) or seamless.
• No difference in performance but seamless is stronger and more expensive.

Question 8

Welded / seamed pipe

Answer 8

• Created by shaping rolls of coiled steel called “skelps” into cylindrical forms and welded along the seam.
• Cheaper but less strong than seamless pipe.
• Most common

Question 9

Seamless pipe

Answer 9

• Fabricated by extrusion: a hot billet is forced through a die at high pressure then over a forming mandrel
• Stronger and more expensive than welded pipe

Question 10

Pipe standards and specifications

Answer 10

• Standards are set out by a standards body (ATSM, BS, CSA, DIN)
• Manufacturer have controls and quality assurance in place to respect the standards
• Steel pipe is broken down into grades : the higher the grade, the stronger the pipe.

Question 11

Piping grades

Answer 11

• General wall thickness classifications:
  1. Standard (STD)
  2. Extra Strong (XS) / Extra Heavy (EH)
  3. Double Extra Strong (XXS) / Double Extra Heavy (XXH)
• Pipe can also come in light wall/ light gauge/ light weight. This is thin pipe used only in specific applications.
• Not a very helpful or ideal method of rating

Question 12

Pipe sizing

Answer 12

Pipes are measured by a nominal inner diameter

Question 13

What are Schedule Numbers?

Answer 13

• A weight classification system used to denote wall thickness
• Better than using grades
• Range from 10 (light wall) to 160 (double extra strong).
• Thinner walls for gas, thicker walls for critical systems or high pressure systems
• Most piping on vessels with be Sch. 40.
• Sch. 80 for critical systems or high pressure, i.e. bilge suction lines or fire mains
• Sch. 120 for steam lines
• Schedule requirement depends on system and regulations

Question 14

Pipe ends

Answer 14

1. Plain Ends (cut perpendicular to the wall)
2. Beveled Ends (ground to an angle to enable welding)
3. Threaded Ends (threaded to the desired standard. In NA, this is taper thread called NPT. This is done to lock/seal to the pipe fitting)
4. Grooved Ends (groove machined about 1/2” back from end, used for groove-lock fittings and joining systems)

Question 15

What finishes can the steel have?

Answer 15

1. Black Iron Pipe
2. Bare metal
3. Pickled
4. Pickled and oiled
5. Galvanized pipe
6. Could also be coated with a paint or sealant, or lined with a suitable material (usually a polymer)

Question 16

What is 1. Black Iron Pipe?

Answer 16

• A steel pipe that has been coated with lacquer to prevent corrosion

Question 17

What is 3. Pickled Pipe?

Answer 17

• A pipe (generally black iron) is pickled when it is placed in a mild acid solution to remove all scale and contaminants from the inside and outside surfaces.
• The pipe will be rendered clean
• Pickling can be done before or after the pipe is installed in a system
• Drawback : the pipe will flash corrode as soon as the pickling process is over and must therefore be coated with some form of rush inhibiter, like oil.
• Most commonly done on installed fuel or lube oil lines.

Question 18

What is 5. Galvanized Pipe?

Answer 18

• A protective coating of zinc is applied on both the inside and outside of the pipe.
• This layer prevents a corrosive fluid (like sea water) from coming in contact with the iron
• Drawback : the coating will peel off if threaded (so coat after threading); the coating will burn off if welded (creating hazardous fumes); cannot be used on domestic fresh water

Question 19

Stainless Pipe

Answer 19

• Composed of an alloy of steel, nickel, and chromium
• Great strength and resistance to corrosion
• Primarily used for the transport of corrosive fluids or gases (Avgas systems and dual fuel LNG systems).
• Expensive and difficult to work with
• Cannot be threaded (therefore, must weld)
• Used sparingly

Question 20

Copper Nickel / Cuper Nickel / CuNi

Answer 20

• Composed of an alloy of copper and nickel
• Great strength and resistance to corrosion
• Often used with high corrosive mediums (sea water) or when fluid must maintain purity (domestic fresh water)
• Expensive and difficult to work with
• Used sparingly

Question 21

Copper Pipe

Answer 21

• Used for HVAC units and domestic fresh water
• Very malleable and easy to work with
• Is considered clean and inert
• Cannot be used in systems with repeat pulsations -> will become brittle and fail (e.g. fuel injector lines); cannot be used for high temperatures; cannot expose to flame
• Can be hard or soft temper, choice depends on application
• Has different method to identify wall thickness and ductility:
  1. Thin : Schedule K (red) heating applications, excellent heat transfer. Not for water as it will erode and fail faster than other types
  2. Medium : Schedule L (blue) domestic fresh water
  3. Thick : Schedule K (green) gasses (natural, propane), HVAC, fire protection systems and vacuum systems.

Question 22

Plastic Pipe

Answer 22

• Lightweight, easy to install
• Must be glued together
• Used only on non-critical systems, not under pressure
• Only for drains and sewage lines and only where approved by Class
• Cannot be fire rated and will melt > 140F
• Not for critical systems or to carry flammable product
  1. ABS: stronger, more shock resistant and better for severely cold temperatures
  2. PVC: more flexible

Question 23

Tubing

Answer 23

• Manufactured to a more exact tolerance than pipes
• Size is indicated to the exact outside diameter of the tube.
  Types:
  1. Mechanical
  2. Structural
  3. Pressure

Question 24

1. Mechanical Tube

Answer 24

• Used for mechanical and light gauge structural applications like support and framing around machinery
• Manufactured to meet specific end use requirements, specifications, tolerances, and chemistries to give more specific property uniformity throughout the tube
• Not intended to carry fluid or gas under pressure

Question 25

2. Structural Tube

Answer 25

• Used for general structural applications like pillars or cages
• Available in round, square, rectangular and other shapes
• Not intended to carry fluid or gas under pressure

Question 26

3. Pressure Tube

Answer 26

• Manufactured specifically for and used to carry fluids or gasses under pressure
• Can be manufactured out of various material: aluminum, copper (HVAC, coolers), stainless steel (hydraulic systems exposed to weather), carbon steel (oil and gauge lines on diesel engines).

Question 27

Pipe Fittings

Answer 27

• The components that allow for the assembly of equipment, valves, and pipes into a functioning piping system
• Can be manufactured from black iron (could be galvanized), brass, bronze, stainless steel or plastic
• Must be the same schedule as the connected pipe
• Choice depends on application

Question 28

What are the functions of fittings?

Answer 28

A. Change direction of piping in a system
B. Connect or join piping or equipment
C. Provide for branches, clean-out, or take-off
D. Block or regulate flow within piping or equipment

Question 29

How are fittings identified?

Answer 29

1. Nominal pipe size or tube size that the fitting is manufactured to fit
2. Type or description of the fitting
3. Joining or connection method of the fitting
4. Material that the fitting is manufactured from
5. Pressure temperature rating

Example : 1” 90 deg Elbow NPT Black Iron 150 WOG

WOG = water, oil, gas

Question 30

2. Types of pipe fittings

Answer 30

A. Elbows
B. Tees & Wyes
C. Grooved Fittings

Question 31

A. Elbows

Answer 31

• Change direction in a piping system
• Designated by the amount of directional change
  1. Straight elbow : same size connection at each end
  2. Reducing elbow : different size inlet to outlet
  3. Street elbow : (external) male thread on one end and (internal) female thread on the other. Low profile, thread directly into the machine.

Question 32

B. Tees & Wyes

Answer 32

• Provide for branches, take-offs, and/or auxiliary connections
  Tee: 90 deg to path of flow, disrupted flow
  Wye: at an angle, usually 45, more smooth. Can also cap to get access to a blockage or clog.

Question 33

C. Grooved Fittings

Answer 33

• A groove is cut or rolled in the pipe a set distance back from the end
• A rubber gasket is slipped over one of the pipe ends and then the two pipes are lined up
• The gasket is slid down to span the gap between the pipes and the whole assembly is held in place by a split metallic collar which slots into the grooves of the two pipes
• Cheap and easy to install and disassemble
• Cannot use with high pressure, fuels or critical systems
• Common on main engine cooling systems

Question 34

3. Joining or connection method of the pipe fittings

Answer 34

A. Unions
B. Couplings
C. Flanges

Question 35

A. Unions

Answer 35

• Make the joining or dismantling of pipe easier and quicker
• Higher potential for leak than couplings
  1. Ground joint : features a ground metal joint (corresponding angle to ensure flush surface) between the two sealing faces
  2. Gasket type : require a gasket or washer to seal between the two union parts. Used for steam systems

Question 36

B. Couplings

Answer 36

• Permanent junction of segments of pipe in a straight line
• Pipes can be the same size or different sizes (reducing coupling)
• Threaded ends or welded
• Cannot drop a segment for repair

Question 37

C. Flanges

Answer 37

• A circular plate welded to one end of a pipe. The flange has a central hole for the passage of fluid and bolt holes all around for joining to another flange.
• Allows for ease of disassembling and separation of piping and equipment for repair and regular maintenance
• Generally welded (high pressure, combustible liquid, or critical systems) to the end of a segment of pipe but could also be threaded
• Sealed with a gasket between the two flange faces
• Flanges are sized to the nominal size of the pipe and the schedule number: the higher the schedule AND/OR the larger the diameter = more bolt holes

Question 38

Distinct types of welded flanges

Answer 38

Distinct types:
1. Welded neck
2. Socket Weld
3. Slip On
4. Lap Joint Flange
5. Blind Flange / Blank Flange

Question 39

1. Welded Neck

Answer 39

A spigot extends past the flange and the pipe is welded to it.
Simple to use, but can be a challenge to weld
Challenge: concentricity (deflection during welding)

Question 40

2. Socket Neck

Answer 40

The flange is recessed and the pipe sits inside before it is welded

Question 41

3. Slip On

Answer 41

The flange is free to slide over the pipe. Care is taken to not extend the pipe past the edge of the flange

Question 42

4. Lap Joint Flange

Answer 42

• Consists of a stub end (welded to the pipe) and a flange. The flange itself is not welded but is slipped over the stub end and is free to turn.
• Used when the alignment of the flange is critical
• Common in exhaust lines, specifically bellows/ expansion joints.

Question 43

5. Blind Flange / Blank Flange

Answer 43

Used when the piping needs to be sealed off for repair or maintenance.
Blocks flow

Question 44

Gaskets

Answer 44

• Must be able to flow or form under bolt compression to fill all irregularities in the flange sealing faces and stopping leakage
• Must be able to withstand possible high service temperatures and corrosive mediums
• Must prevent system pressure from blowing out the gasket
• Type used depends on application

Question 45

Gaskets are available for three flange face types

Answer 45

1. Full face gasket : covers the full face or area of the flange, use bolt holes to place but must be well manufactured
2. Flat ring gasket : covers only the sealing area or raised face of the flange, easy to line up because there are no holes but hard to keep concentric
3. Metallic Ring gasket aka Spiral Wound Gasket : gasket material is held inside a metallic ring. The inner ring is resistant to the medium in the system; the middle ring is spiral wound; an outer metal ring holds everything in place. Used for high temperature and high pressure flanges (e.g. exhaust or steam) or highly corrosive/erosive fluids

Question 46

Gasket materials

Answer 46

• Available in many thicknesses -> thickness depends on application
• Available in many materials -> material depends on application
• AKA Jointing AKA Sheet Packing
  1. Rubber gaskets
  2. Foam AKA sponge gasket
  3. Fibre gasket
  4. Paper gasket
  5. Cork gaskets
  6. Graphite gaskets
  7. PTFE gaskets

Question 47

1. Rubber gaskets

Answer 47

• Characteristics will depend on manufacturing process
• Many types of material available and choice depends on application
• May be fabricated with additives to make the rubber stronger or may have string inside to give radial strength
• Some are more fuel resistant than others
• Ensure material selection is suitable for application and meets all Class Requirements
• Great for water, compressed air, HVAC.
• Cannot use in high temperature or with oil

Question 48

2. Foam AKA Sponge gasket

Answer 48

• Covers all materials made from closed cell foam rubbers
• Properties of foamed rubber are the same as parent rubber
• Used for low pressure applications
• Commonly used for equipment seals, dust, moisture and splash seals and lid seals
• Choice of foam will depend on application

Question 49

3. Fibre Gasket

Answer 49

• AKA Klinger Gasket (trade name)
• Also called synthetic gaskets
• Composed of compressed fibres (cellulose), similar to paper making process
• Many different types of fibres are used to produce gaskets with differing strengths, pressure and temperature ratings.
• Suitable for pressures up to 100 bar and temperatures up to 400 C
• Great for steam and oil
• Commonly used for compressor air, lube and fuel oil systems, low pressure steam, or to seal components on diesel engines
• Can be difficult to work with

Question 50

4. Paper gasket

Answer 50

AKA oil paper AKA cellulose gaskets
- Relatively cheap to manufacture and used commonly
- Paper is impregnated with a substance that makes it resistant to oil, fuel, air, water, alcohol, grease, and most solvents
- Commonly used in engines, pumps, and in piping
- Low pressure, tight tolerance, good clearance

Question 51

5. Cork gaskets

Answer 51

• Properties depend on the size of the granules used in the manufacturing AND on the base rubber compounds with which the material is bonded
• Cheap and effective
• Good oil resistant properties
• Used for sealing engine sumps, crank case covers, inspection doors and valve covers
• Only used in low pressure applications

Question 52

6. Graphite gaskets

Answer 52

• Used in specialty applications
• Manufactured from flake graphite chemically treated then mechanically worked into large sheets
• Typically used in high temperature and high pressure applications (high pressure steam and exhaust gas piping)
• Resistant to corrosion but very expensive and brittle

Question 53

7. PTFE gaskets

Answer 53

AKA Teflon
- Excellent chemical resistance
- Non-conductive, no static electricity
- Buy in sheets and cut to the dimensions required
- Used in the presence of highly corrosive chemicals OR when a non-conductive gasket is required (e.g. AVGAS)

Question 54

Pipe support

Answer 54

• Can be from above or below
• Needed to support pipes from vibrations to prevent pipe fracturing
• Location and spacing will depend on the size of the pipe, the system, and the path of the system
• Generally a minimum of every 8 ft but could be closer
• Most common type is a pipe clamp

Question 55

Pipe clamps

Answer 55

• Most common type of pipe hanger found on a ship
• Rule of thumb: every 6 feet (could be closer is required e.g. bend in the pipe, high vibrations)
• Consists of two pieces of flat bar bent to the profile of the pipe and the bars are bolted together around the pipe
• The clamp is then connected to the ship structure from above or below
• Copper and plastic pipes require a gasket between the pipe and the clamp to protect from chafing

Question 56

Expansion joints

Answer 56

• Necessary in systems that contain high temperature mediums (steam or exhaust gasses)
• As the pipe heats up, it will expand longitudinally and if allowances are not made, the pipe will buckle and fracture
• These joints will also absorb movement and vibration, so commonly used where pipes connect into machines
  A. Bellow
  B. Loops

Question 57

A. Bellows

Answer 57

• Manufactured from metal (commonly stainless steel) or rubber
• Made up of a series of one or more convolutions, where the shape is designed to withstand the internal pressures of the pipe but flexible enough to accept axial, lateral and/or angular deflections
• No user serviceable parts -> cannot fix, must replace

Question 58

B. Loops

Answer 58

• Commonly seen in high pressure high temperature steam installations
• More commonly seen on an open deck because it requires space

Question 59

Color Coding Standards for Piping Systems

Answer 59

• Color code is used in conjunction with written identification (labels)
• Used to identify the fluid or gas being conveyed in the system
• Standardization system to rapidly identify the pipe and its contents for tracing and troubleshooting and isolation in an emergency
• Consists of primary color (purpose?) and secondary color (medium?) *NOTES CONTRADICT HERE
• Here, pipe systems include the pipe line or conduit itself PLUS the valves, fittings, operating accessories, pipe coverings, and pipe installations. All of these must be identified with the color code

Question 60

Identification location requirements

Answer 60

• Identification (writing and color) must be easily visible and marked at least once in every space or compartment AND every 15 meters (50 ft) in open areas.
• Must be identified on both sides of decks and bulkheads
• If concealed in a pipe case, tunnel or other confined space, must be identified at point of entry and exit and at each access opening
• Must be identified at the starting and ending points of runs, at each piece of equipment, and at branch line junctions

Question 61

Where is the Color Coding Standard posted?

Answer 61

A. Motor control room or station
B. Machinery spaces
C. Wheelhouse
D. Fire Control station (other than wheelhouse)
E. Engineer’s office

Question 62

Primary colour codes

Answer 62

Red : Fire fighting
White : Combustion exhaust (red secondary), Refrigerant (orange secondary), Acids & alkalis (purple secondary)
Yellow : Oil
Orange : Air
Black : Bilge, Sewage
Grey : Grey water
Green : sea (raw) water
Blue : Fresh water
Purple : Steam
Brown : Fuel oil