Gaskets and Piping Flashcards
What are pipe blinds?
Slim discs that are placed between pipe flanges.
These are used for LOTO purposes.
What are the two types of pipe blinds mentioned in the module?
- Pancake style
- Spectacle style
These are in-line blinds, and should not be confused with flange blinds, which are used to close off the ends of piping systems.
As it pertains to piping, what are volute blinds?
Blinds that are used to seal the pump volute after removing the pump body.
What is the main disadvantage of pancake blinds vs. spectacle blinds?
Pancake blinds → the flanges have to be spread in order to remove the blind.
Vs. spectacle blinds, where the piping system is designed to accomodate the blind.
With piping blinds, a ____ blind is installed in a piping system that is designed to accomodate the blind, and doesn’t require the flanges to be spread to install it.
Spectacle blinds
How many gaskest are required for:
1. Spectacle blinds?
2. Pancake blinds?
3. Flange blinds?
- Spectacle → 2 gaskets
- Pancake → 2 gaskets
- Flange → 1 gasket
What are three hazards that need to be monitored for when purging a piping system?
- Toxic compounds
- Explosive gases
- Insufficient oxygen
Normal O₂ levels should be around 21% to 22% by volume.
What precautions need to be taken when purging a piping system with CO₂?
CO₂ forms a corrosive substance when mixed with water.
Precautions should be taken if there is a chance that this can happen.
As it pertains the gas detection, OH&S regulations require that you implement procedures to safeguard against what two things?
- Hazards related to the presence of harmful substances.
- Lack of oxygen where workers a present.
What formula is used to convert psi to in.Hg?
Pressure(in.Hg) = Pressure(psi) × 2.036
1 psi = 2.036 in.Hg
This type of gas detector is a hand-held unit that consists of a bellows-type pump and detector tubes.
Sniffer gas detector
Changing the type of detector tube changes the type of gas detected.
How do the detector tubes work in a sniffer type gas detector.
The gas will cause the reactant in the tube to change colour.
The degree of colour change indicates the concentraction levels of the gas.
This type of gas detector contains sensors, controllers and alarm indicators all in one portable unit that is designed to clip to clothing.
Personal gas detectors
These are often called sniffers
What is the %LEL of a gas?
% lower explosive limit
This is the lowest concentration of a gas or vapour that will burn in air.
What needs to be taken into consideration when mounting permanent gas detectors?
The characteristics of the gas
Heavier gas, the sensor will be mounted closer to the ground, while lighter than air results in the sensor being mounted higher up.
What are the common types of gasket joints used in industry?
- Flat face (unconfined)
- Raised face (unconfined)
- Tongue and groove (confined)
- Male and female flange (partial confinement)
- Ring joint (self-confined)
These gasket joints are essential for preventing leakage in various applications, including turbines and compressors.
What is the purpose of a gasket in a sealing application?
To fill the voids or irregularities of the joining faces of the mating parts
Gaskets are softer sealing elements that help achieve a proper seal by accommodating surface imperfections.
True or False: Practical static sealing does not depend on the smoothness of sealing surfaces.
False
Smooth sealing surfaces are crucial for effective sealing and minimizing leakage.
True or false: The ring joint is classified as self-confined.
True
Self-confined joints provide a specific sealing mechanism that does not rely on external pressure.
What machining processes can be involved in achieving sealing surfaces?
- Machining
- Grinding
- Lapping
These processes are vital to ensure the sealing surfaces are sufficiently smooth to prevent leakage.
What is meant by ‘static sealing’?
Forcing a softer sealing element to fill the voids of mating parts
This concept emphasizes the need for proper contact between the gasket and the surfaces to achieve a leak-proof seal.
What is the significance of surface smoothness in gasket applications?
Smoother surfaces seal better.
Smooth surfaces help ensure better sealing and reduce the risk of leakage.
What type of joint is the ‘tongue and groove’ classified as?
Confined
This type of joint provides a more secure fit and minimizes the chance of leakage.
Identify if the following flanges are confined/unconfined/partially confined/self/contained:
- Flat face
- Raised face
- Tongue and groove
- Male and female flange
- Ring joint
- Flat face → unconfined
- Raised face → unconfined
- Tongue and grove → confined
- Male and female flange → partial confinement
- Ring joint → self-confined
What does it mean when a flange is “confined”?
Where the gasket in the flange is located within a recess or groove.
This provides for better sealing, but makes it more difficult to replace the gasket.
What is the main difference between an O-ring (squeeze type) and a flat gasket?
The O-ring’s sealing ability increase as internal pressure increases.
With static O-ring seals, the O-ring must protude by ____% above the land in order to ensure proper sealing.
10%
A flat gaskets sealing ability is affected by what three things?
- Thickness of the gasket
- Bolt load pressure it has to withstand
- Internal and hydrostatic end forces
What are the two types of flange finishes?
- Smooth
- Serrated
What are the two types of serrated flange finishes?
- Concentric groove
- Spiral groove (phonographic)
When it comes to a serrated flange finish, what is a phonographic finish?
The same as a spiral groove.
Identify the following type of serrated flange finish:
Concentric grooved face
Identify the folloiwng type of serrated flange finish:
Spiral grooved face.
This type of gasket joint allows the gasket to flow freely, either towards or away from the fluid pressure under loading and are primarily used where system pressures are low to moderate.
Flat-faced unconfined
What can happen to a flat faced unconfined gasket joint if the system pressures are too high and the bolt loading is too light?
The gasket can blow out.
This is an unconfined gasket, so there is nothing holding it in place aside from the bolt loading.
What is the maximum pressure that a raised face unconfined gasket should be used to?
900 psi
What do the three markings on a raised face unconfined flange indicate?
- pipe size ∅
- pressure class (not pressure rating)
- ring joint groove number (if any, these may be excluded)
Identify the type of flange along with what the markings on the flange indicate:
Flange → Raised face unconfined flange
Ax3 → Trademark/company name
6” → nominal pipe size
300 → Class 300 pressure rating
Do not confuse Class 300 pressure rating as the pressure rating. Class 300 ≠ 300 psi.
With raised face flanges, a raised flange face of 1.________” is generally used for pressure classes up to 900, while a rasied flange face of 2.________” is used for pressure classes above 900.
- 1/16”
- 1/4”
This type of flange and gasket design provide the gasket no freedom to move and is considered good for high-pressure applications.
Tongue and groove confined gaskets
What is the primary purpose of a gasket:
a) To separate two flanges.
b) To form a seal between flanges and equipment housings.
c) To reduce noise in piping systems.
d) To increase bolt tension.
b) To form a seal between flanges and equipment housings.
True or false: In general, tongue and groove confined gaskets use a metallic gasket.
True
This has to do with the higher pressures seen with this type of flange.
- What is the main advantage of tongue and groove gaskets?
- What is the main disadvantage?
- They help to centre the gasket.
- They require closer tolerances and care in connecting.
What does it mean when a gasket is semi-confined?
The gasket is confined on its two flat sides and on the outside edge.
One edge (the inner) is free to move.
This design provides good support for the gasket and protection from blowout because of the confinement provided by the outside edge.
This type of flange design is basically a flange face that has grooves machined into both flanges, and is a good choice for high-pressure, high-temperature and corrosive environments.
Self-contained ring joints
This type of gaskets are compact and adapted for high-pressure, high-temperature and corrosive conditions.
Solid metal ring gaskets
Why do solid metal ring gaskets not need a high level of bolt loading to achieve a tight seal?
The ring has a wedge like shape that concentrates the sealing pressure under bolt loading.
The flanges used with this type of gasket must be harder than the gasket.
What are three common designs of solid metal ring gaskets?
- Delta seal ring
- Oval seal ring
- Octagonal seal ring gaskets
When disassembling solid metal ring gaskets, how should the flanges be moved away from each other during disassembly?
They must be pulled straight back.
This is due to the rings sitting a groove, which prohibits them from being slid out until there is enough flange separation.
Where is the greatest compressive force exerted on a gasket in a flange?
Closest to the bolt circle
What is a critical consideration when choosing a gasket material?
a) Ability to withstand UV radiation
b) Compatibility with flange and joint design
c) Color of the material
d) Weight of the gasket
b) Compatibility with flange and joint design
True or false: Gasket thickness has no effect on the alignment of internal components.
False
Changing gasket thickness can cause pipe strain.
True or false: The material of a gasket must be able to flow into irregularities of mating surfaces under bolt loading.
True
This provides the sealing ability of the gasket.
True or false: Gaskets are unaffected by temperature extremes and corrosive environments.
False
Gasket material must be compatible with the medium it is sealing.
This type of gasket covers the entire flange and the bolts that hold the flange together are accomodated in the gasket design, which requires all the bolts to be removed and the flange separated in order to remove and replace the gasket.
Full face gaskets
This type of gasket are used in both flat face and rasied face gaskets, and only require some of the bolts to be removed in order for the gasket to be removed and changed.
Flat ring gaskets
This type of gasket is made of stainless stell with a non-metallic insert and is most often found in high-pressure and high-temperature applications.
Spiral wound gaskets
True or false: Spiral wound gaskets can tolerate minor changes in system pressure, vibration, thermal shock and slight flange separation and still maintain sealing integrity.
True
This type of gasket is made of a metallic jacket that covers a non-metallic filler, which is commonly asbestos.
Metal-jacketed gaskets
What type of gasket material would be selected for use in corrosive and high-temperature situations?
metals
What is a gasket compound?
Adhesives and sealants
These are also called sealing pastes.
With sealing pastes, a 1.________ is used for gaskets because they prevent the leakage of some medium, while 2.________ are used to hold materials together.
- sealants
- adhesives
Sealing paste = gasket compound
Together, these make up the two classes of gasket compounds.
What does it mean if a sealant is anaerobic?
It can cure without the presence of oxygen.
When fabricating a gasket, what are the two methods that can be used to obtain the proper bolt hole spacing for the bolt layout?
- angle method
- chord method
When fabricating a gasket, what is the angle method for laying out the bolt holes?
360º ÷ # of bolt holes
Use a set of dividers or protractor to scribe them on the material at the bolt hole circle radius, then punch or cut them out.
When fabricating a gasket, what is the chord method for laying out the bolt holes?
Bolt hole ∅ x chord length
This gives you a straight distance between each bolt hole.
What formula is used to calculate the chordial distance when calculating a bolt hole circle?
CD = BCD x sin (180 ÷ n)
cd = chordial distance
BCD = bolt circle diameter
n = number of bolt holes
When fabricating a gasket, the bolt holes should be ____” larger than the bolts.
3/32”
What precautions need to be taken when storing cork and cellulose fibre gasket material for extended periods of time?
Cork and cellulose becomes brittle with age.
These have a shelf-life.
What effect does UV and heat have on gasket material?
It deteriorates it.
Gasket material should be protected from UV sources and heat.
True or false: Hanging gaskets is a good way to store gaskets.
False
Some gasket material can creep and distort if hung. Gaskets should always lay flat when being stored.
What formula can be used to calculate the output of a torque multiplier if losses are known?
Tw = Tf ÷ (R x eff)
Tw = torque wrench setting
Tf = final torque
R = torque multiplier ratio
eff = losses ⟶ 15% loss would be 100 - 15 = 85, or 0.85
This type of piping material offers excellent corrosion resistance, but is much heaiver than steel and should not be used with hydraulics due to the fact that they catalyze (speed up) the oxidization of hydraulic fluid and become work harden and brittle.
Copper and brass (copper and zinc)
True or false: Cast iron piping is used because of it’s corrosion resistance.
True
What are two ways that piping is manufactured?
- welding
- extrusion
With pipe, a straight seam weld is most suitable for producing pipe less than ____ inches in diameter, while a spiral seam weld is commonly used on larger pipes.
60 inches
Which type of weld seam is most suitable for piping under 60” in diameter?
straight seam
Which type of weld seam is most suitable for piping over 60” in diameter?
spiral seam
This type of pipe is produced by forcing a hot billet of steel through form rollers and over a mandrel or a piercing plug simultaneously.
Extruded pipe (seamless)
What is another name for extruded pipe?
seamless pipe
True or false: Extruded pipe is most suitable for producing piping under 2” in diameter.
True
What kind of fittings are grooved end pipe used with?
Victaullic pipe fittings.
This are used on pipes that are at least 3” in diameter.
This type of pipe surface finish is the standard finish and consists of a coating of lacquer to prevent corrosion in transit.
Black iron surface finish
This surface finish results in a black shiny appearance.
This type of pipe surface finish is ideal if the pipe is to be submerged in a non-corrosive fluid that you do not want to conaminate with a coating that might flake off.
Bare pipe finish
This pipe has no coating.
This type of pipe surface finish provides a relatively cheap corrosion protection against attack by less aggressive corrosives.
Galvanized pipe finish
True or false: Galvanized pipe can be used in hydraulic service as long as the pressure is limited to below 2000 psi.
False
Galvanized piping should not be used in hydraulic service because the zinc coating can flake off.
True or false: The zinc coating on galvanized piping catalyzes the oxidization in hydraulic oil.
True
Catalyze = speed up
This, along with the issue of the zinc flaking off and creating blockages, is why this piping should not be used with hdyraulics.
This type of piping surface finish has been washed with acid to remove all traces of oil, and is then sealed and purged with dry nitrogen.
Pickled pipe
Which type of pipe surface finish is used for ammonia service and for all refrigerant lines?
Pickled pipe
This type of piping surface finish is used for hydraulic piping, as it minimizes contamination during construction of hydraulics.
Pickled and oiled pipe
What is yellow jacketed pipe used for?
Underground service
What are the four pipe weight classifications and what types of pressures would they be used with?
- Lightweight (light wall, light gauge) ⟶ sprinkler applications
- Standard weight (Std.) ⟶ low-pressure (hydraulic return lines)
- Extra strong (XS) ⟶ high-pressure
- Double extra strong (XXS) ⟶ the highest of pressures
True or false: Extra strong (XS) and extra heavy (XH) pipe have the same wall thickness.
True
What are the two ways pipe wall thickness is specified?
- weight designation (Std. XS, XXS, etc.)
- Schedule (10, 20, 30, 40, etc.)
True or false: Double extra strong (XXS) and double extra heavey (XXH) pipe have the same wall thickness.
True
What schedule of pipe is considered standard?
Schedule 40
With schedule pipe sizes, that larger the number, the ________ the pipe wall.
thicker
True or false: Nominal pipe size (NPS) is based on the ID, even though the ID is not the same for different weight pipes.
True
NPS is about the same as the ID of a standard weight pipe.
With pipe sizes, ID is used for selecting pipe up to ____ inches in diameter, while OD is used for anything over that.
12 inches
With piping, why is the OD kept constant for different weights of pipe?
So a standard die and standard fittings are able to fit pipes of different wall thicknesses.
True or false: Although tapered threads are reusable, the threads have a tendency to stretch and weaken after they have been tightened frequently.
True
What is the main limitation of threaded pipe joints?
They are prone to loosening and leaking when exposed to vibration.
What effect does the wedging action of threaded pipe have on any component that it may be threaded into?
Distortion.
The wedging action of the taper produces high stresses in the joint that tends to distort any component which the joint is attached.
What are Gruvlok pipe fittings?
The same as Victaulic fittings.
This type of pipe hanger allows the pipe unlimited axial movement with minimum resistance.
A roller hanger
This type of pipe hanger allows a horizontal pipe to move up and down freely.
A spring hanger
What type of pipe support would be used to support a pipe that is moving horizontally through floors?
A pipe riser clamp
What is soldering?
The process of joining two metals with non-ferrous (solder) at a temperature lower than welding
True or false: When soldering, the base metals are melted to the solder filler.
False
The base metals are not welded when soldered.
True or false: Soldering is considered a high-strength joint.
False
It is a low strength joint.
What are three common applications for soldering?
- Joining electric wires and contacts.
- Sealing crimped or folded joints on containers
- Joining sheet metal and tubing joing under low stress
What are the three main advantages of soldering vs. welding?
- Less distortion
- Two different metals can be joined
- Heat-treated parts are not affected
What is a key requirement for gasket materials regarding bolt load?
The ability to withstand the bolt load without being crushed
This ensures that the gasket maintains its sealing properties under pressure.
What must gasket materials be able to withstand in terms of environmental/operating conditions?
Pressure and temperature extremes
Gaskets must maintain integrity under varying operational pressures and temperatures.
What is an important factor in selecting gasket materials related to fluids?
Fluid compatibility
Gaskets should not react negatively with the fluids they come into contact with.
What compatibility must be considered regarding gasket materials and flanges?
Compatibility with flange and joint design
The gasket must fit properly within the joint to ensure an effective seal.
What type of wear should gasket materials be able to withstand?
Wear experienced by the turning motion found on drain plugs (attrition)
This is crucial for gaskets used in applications with moving parts.
What is the product in a sniffer tube called?
Reactant
What type of reamer is used on a power threader?
Straight fluted
Sprial fluted reamers pull into the material, which could cause breakage with a power threader.
True or false: 1 inch schedule 80 and XXS pipe have the same outside diameters.
True
When making repairs to an existing piping system what must be ensured, what four pipe characteristics must be ensured?
- Pipe material
- Size
- Finish
- Standard
Identify the standards organizations used in North America for piping?
CSA, API, ASTM and ISO
The heat number found on a Mill Certification for piping tells you what?
Record of the chemical analysis of the steel
With a pipe end finished “threaded and coupled”, the coupling supplied with this type of finish is suitable for what piping application?
These coupling are thread protectors and should not be used in any installation
Which pipe joint is prone to loosening during operation in a system which vibrates, has pressure pulse and thermal movement?
Tapered threads
Which pipe joint requires a machined spot face?
Straight threads
ORB ⟶ O-ring boss threads
When cutting a NPT thread how far do you cut the thread?
Thread to the end of the die
How many turns by hand should a fitting have on a ½ inch NPT threaded pipe?
4 ½
How do you determine the outside diameter of copper tube?
Tube is measured by nominal size plus 1/8 on an inch
Which type of soldering equipment would be practical for soft soldering a large area?
Coppers
Which type of flux is suitable to solder electrical wiring?
Resin flux
Identify the following flange and gasket design:
Flat-faced unconfined
Identify the following flange and gasket design:
A male and female flange and gasket
These gaskets are semi-contained because the gasket is confined on its two flat sides and outside edge.
This type of pipe support allows unlimited axial movement for supported pipe.
Pipe saddle support
What are two reasons why gaskets move while in place?
- Bolt load
- Internal pressure
True or false: Flat-faced gasket joints are regarded as confined joints because the gasket is not allowed to flow freely.
False
The gasket can be squeezesd out.
True or false: Flat-faced gaskets are used for high-pressure conditions.
False
They would be squeezed out.
