LABS - 5A: Assembly station

Question 1

What are typical materials for pipe construction?

Answer 1

Aluminium (Can withstand high temp’ and pressure)

Copper (Resistant to corrosion. Used for plumbing)

Titanium (Withstand high temp, pressure and is resistant to corrosion)

Plastics (Non-corrosive and chemical resistant. Used for sewage and water pipes)

Concrete / ceramic (Withstand low pressures. Used for drainage)

Stainless steel (Corrosion resistant. Used for sanitary piping)

Question 2

What are the 4 main types of pipe connection?

Answer 2

Welded (non detachable)

Flange (Detachable)

Screw (Detachable)

Socket (Detachable unless welded)

Question 3

What are pipes used for?

Answer 3

Transfer of fluids. Carrier media (air/water) can also transfer solid substances in 2-phase mixtures.

They also carry out chemical and physical processes (cooling, mixing, chemical reactions etc.)

Question 4

What are pipe fittings?

Answer 4

Pre-produced shaped sections of pipe in the form of bends, branches, diameter reductions and gates.

Question 5

What are flanges?

Answer 5

Connecting elements for detachable pipe connections. They’re mainly used for connecting additional components e.g. control fittings, pumps and vessels, to pipes.

Question 6

What are control fittings?

Answer 6

Shut-off devices or actuators. They’re used to shut off and open pipes (switching) or to regulate flow rates (adjustment) and to protect systems.

Question 7

what does the notation Iw represent?

Answer 7

Bore (pipe’s inner diameter)

Question 8

What is DN?

Answer 8

Nominal diameter

It’s a value that’s used to identify compatible pipe features and components.
It has no unit and is approx. equal to the piping component bore, Iw.

Question 9

What is PN?

Answer 9

Nominal pressure

It’s the characteristic feature for pressure levels, in which piping parts with identical designs and connection figures are grouped.

It specifies the max permissible +ve operating pressure in bar.

Question 10

What are cutting ring fittings?

Answer 10

A type of screw connection.

It’s easy to assemble and prevents leaks. Usually used for pipes with low DN.

Question 11

What are gate valves?

Answer 11

shut-off devices that completely shut off a pipe or open its full cross-section. Their task is not to regulate a material flow.

When installing the gate valve, the spindle must always be vertical. For other installation positions, e.g. horizontal, at larger nominal diameters it must be ensured that no flexural stress occurs at the spindle, the upper housing section, the piston rod etc., as otherwise proper functioning of the drives and sealing of the gate valve can no longer be guaranteed.

Question 12

What are ball valves?

Answer 12

Valves with a spherical gate with cylindrical flow aperture.

Turning the gate by 90° with a lever enables a straight flow to be set or the pipe to be completely shut off. When open, there is practically no flow resistance.

Ball valves offer the following advantages: fast opening and closing, small operating distance, low flow resistance in open position, small dimensions, self-cleaning sealing surfaces, and ball valves can be installed horizontally or vertically.

Question 13

What are non-return valves?

Answer 13

Valves used where a reverse flow is not permitted. They must fully seal off the return direction while offering the lowest possible resistance in the forward flow direction.
If the differential pressure of the medium falls below a value determined by the spring force, the valve closes.

Non-return valves are installed in the direction of flow in pipes, and must close if the pressure drops or if a high back-pressure occurs. The gate is a disc with sealing strip. When the flow comes to a stop, the sealing disc is pressed onto the sealing surface by a spring. Non-return valves are largely maintenance free and low wearing. They must fully seal off the return flow while offering the lowest possible resistance in the forward flow direction.

They should only be installed horizontally or vertically as an angled installation location can influence the opening pressure.

Question 14

What are shut-off valves?

Answer 14

Valves used to shutoff and restrict the flow of media. They must shut off the flow without leaks.

To prevent shock loads they should close in such a way that the volumetric flow does not suddenly drop to zero.
The valve taper is moved by the spindle and metallically seals against the seating ring pressed into the housing.

The spindle is sealed by a gland. The joint between the housing and the clamp cover is sealed by a flat seal. Shut-off valves can be installed horizontally or vertically.

Question 15

What are dummy discs?

Answer 15

Dummy discs are used if a pipe is to be closed for a longer period or to prevent accidental opening of one or more control fittings resulting in a flow, e.g. for repair work. Perforated discs reduce the flow aperture of the pipe.

A dummy disc consists of a metal disc with two seals, which is inserted and screwed into a flange connection.

Question 16

What are condensate drains?

Answer 16

Control fittings that automatically drain the condensate that forms in steam pipes and any entrained liquid from the pipe without the steam itself escaping from the pipe in significant quantities.

If a pipe carrying steam or gas contains liquid, it is carried along by the fast flowing gas and results in water hammer when it impacts on fittings in the pipe.
This can damage both the pipe and the control fittings. Therefore, condensate drains must be installed in pipes that will be used for steam.

Question 17

What’s inspection glass?

Answer 17

Inspection glasses are flow indicators for liquids.

The significant deflection of the flow in the inspection glass results in turbulence, which makes the flow of the liquid visible. It also allows the user to draw conclusions about any faults in the piping system, e.g. estimating the flow volume.
Dirt, colouration and foreign particles can be identified.

Question 18

What does a dirt trap do?

Answer 18

The liquids and gases flowing through the piping system can contain impurities. The pipes, but particularly the control fittings, can thus be contaminated and, over time, become clogged. To prevent this, filters are fitted as a dirt trap at the inlet to the pipe to retain any impurities.

Filter materials are normally wire cloth or fine pored bodies

Question 19

How can pipes and control fittings be represented?

Answer 19

Technical drawings

3D piping diagrams

Isometric piping diagrams

P&ID (Piping and instrumentation diagrams)