Monday, February 16, 2009

PIPING QUIZ & ANSWERS

Piping QA FLUOR DANIEL

PIPING QUIZ & ANSWERS

 

Piping QA

1. What is the pipe size range, per Fluor Daniel standard, for pipe spools that are to be shop fabricated?

3” diameter and larger <2.1/2” and larger>

2. What is the pipe size range, per Fluor Daniel standard, for pipe spools that are to be field fabricated?

2” diameter and smaller

3. Define what piping is considered field assembly.

Off-the-shelf components that make-up a piping assembly and do not require cutting and / or welding

<If no field fabrication is required>

4. Define what piping is considered rack loaded, per Fluor Daniel standard, and what pipe size ranges is involved.

Piping in the PIPERACK that crosses two or more supports.

3” and larger.

5. All shop fabricated piping spools (mark pieces) are shipped from the fabrication shop in a geometry that is defined by length, width, and height. Assuming it to be a box, there are two situations that you must avoid in regard to the box and the mark pieces within. Describe these two situations and describe the undesirable result if you do not avoid them.

Piece mark must fit within the shipping box otherwise it may not be transported.

Skewed placement of the piece mark within the shipping box could result in crowding out other piece marks.

<Press fit should be avoided to ensure piece mark fits shipping box>

6. Define a field weld (FW) and when it is used.

Field Weld is made somewhere other than the fabrication shop. Used to connect two mark pieces (or components) together.

Describe three things you must consider when locating a field weld and why they must be considered.

Accessibility:

The weld must be in a place that is accessible to the welder

Constructability:

The weld must be placed so the constructors can position the piece mark prior to welding.

Size of spool piece to ensure it fits shipping box and can be transported.

Economics:

Made in a location that would lessen or eliminate the need for additional scaffolding.

Piping QA

Self-supporting so temporary supports are not required during construction.

Made on the smaller side of a reducer.

Preferably made in the horizontal

8. Describe a field fit-up weld (FFW) and when it is used.

Field Fit Weld is a weld made somewhere other than the fabrication shop. The fabrication shop adds additional length of material to the spool piece. This additional length gives the field variance for adjustment when the location of the connecting point is not known.

<May require field alteration>

9. Per Fluor Daniel standard, what is the construction (fitting type) of:

Pipe size range 2 ½” and larger? Butt-weld

Pipe size range 2” and smaller? Socket Welded

Pipe size range 2” and smaller? Screwed or Threaded

10. What is the minimum (not absolute minimum) distance between welds that Fluor Daniel likes to use?

3 inches

11. What is the absolute minimum distance between welds (used only as a last choice)?

Pipe Size (NPS) Min. distance b/w welds

1/8” 3/16

1 /4” 1/4

3/8" 5/16

1/2" 7/16

3/4" 1/2

1" 11/16

1 1/4" 13/16

1 1/2" 15/16

2" 1 3/16

2 1/2" 1 9/16

3" 1 3/4

3 1/2" 2

4" 2 1/4

5" 2 3/4

Half the outside diameter of pipe (6” and larger)

12. What do the letters HAZ mean?

Heat Affected Zone

Kavimagi Page 3 of 13 13. What is the effect of the HAZ?

Weakens the material (pipe wall)

Piping QA

14. How far from the weld, is the HAZ?

¼” or 1”

15. Why do piping designers care about the HAZ?

If two HAZ’s overlap each other it may result in failure of the pipe

16. When is the HAZ considered in threaded construction?

When threaded connection is seal welded

17. What are the pressure ratings of forged steel Socket Weld Fittings?

3000#

6000#

18. What are the pressure ratings of forged steel threaded fittings?

2000#

3000#

6000#

19. What are the pressure ratings of malleable iron threaded Fittings?

150#

300#

20. What are the pressure ratings of cast iron threaded fittings?

125#

250#

List the wall thickness for pipe, starting with the thinnest wall to the heaviest wall:

Carbon Steel & Alloy steel (13 schedules)

Sch 10,

Sch 20,

Sch 30,

Sch 40,

Std Wt,

Sch 60,

Sch 80,

XS,

Sch 100,

Sch 120,

Sch 140,

Sch 160,

XXS

Stainless Steel (4 schedules)

Sch 5S,

Sch 10S,

Sch 40S,

Sch 80S

Piping QA

22. What is the technical term used for the sag in pipe caused by gravity and how does affect piping design?

Deflection

It govern the amount of pipe span

<causes leakage at flanges>

<causes stress on pipe>

23. If one 4” carbon steel pipe is schedule 40 and another 4” carbon steel pipe is schedule 80….

Which has the greater sag and why?

4" sch 40 has the greater sag because its wall thickness is less than the wall thickness of the sch 80 - the thinner the wall, the shorter the length the line will span.

Which weighs more and why?

4" sch 80 because it's wall thickness is more than that of the sch 40, more material= more weight

Which requires fewer support point and why?

4" sch 80 because it's thicker wall allows it to span farther, reducing the number of times support is needed.

<more rigid / stiffer>

24. Pipeway/Piperack loading/stuffing drawings.

Which lines qualify for loading/stuffing

Lines 3" and larger that cross two or more pipe supports.

Why is loading/stuffing done (the advantages)?

It provides an early start for construction.

It reduces the amount of ground area taken by storage of pipe

25. Line size changes

When is swage used for a line size change?

When reducing from or to socket welded or threaded construction on at least one end.

When is a butt-weld reducer used for a line size change?

When reducing from or to butt welded construction on both ends.

When/where do you use eccentric, bottom flat swages or reducers and why?

In any horizontal run of pipe, that has two or more supports within that run.

To maintain a common bottom of pipe elevation for the two line sizes.

When/where do you use eccentric, top flat swages or reducers and why?

Used at the final reduction on a pump end suction line.

Piping QA

To prevent cavitation of the pump.

When/where do you use eccentric, side flat swages or reducers and why?

Used when two equipment connections are so close that the two connecting, adjacent lines interfere with each other after the line size change.

If they are side flat toward each other, the lines may clear.

<Used on vertical pipe to maintain common back of pipe>

When do you use butt-weld reducing 90 degree elbows and why?

Normally it is not FLUOR piping practice to use reducing butt-weld 90 degree reducing elbows.

If they are used, it will be where a size change is required and there is insufficient space available for an elbow and a reducer or an elbow and a reducing flange - or if the client requires it.

Why would a short radius butt-weld 90-degree ell be used?

To adhere to FLUOR piping practice 000 250 2650 where it states 10" and larger elbows at a nozzle of a vertical vessel are short radius (decreases the "l" dimension so a standard vessel pipe support can be used).

<Space limitations>

Why would a short radius butt-weld 90-degree ell not be used?

It is easy to "lose" a short radius elbow if shipped to the jobsite or fabrication shop with long radius elbows of the same size.

Additional tracking effort may result to keep the short radius elbow from being "lost" or used inadvertently where it was not intended to be used.

Often the use of a short radius elbow requires client approval, or process review, or stress approval - all taking time that would not be taken for a long radius elbow.

<when pressure drop is a concern – short radius elbow has more pressure drop.

26. What is a trimmed ell and when is it used?

A trimmed elbow is a butt weld 90 degree long radius elbow that is cut and beveled to match the original bevel, the resulting change of direction is no longer 90 degrees but is a non-standard angle suited for the piping geometry requiring it.

Trimmed elbows are used when a line routing must have a change of direction that is not satisfied by a 90 or 45-degree elbow or by elbows being rolled or offset.

Describe a stub-on connection and when it is used?

A stub-on connection is a branch connection made to a header without the use of fittings - the connection is made from pipe. the branch pipe is contoured (fish-mouthed) to match the curvature of the header to which it will be connected (a fillet weld). A hole is made in the header that should match the inside diameter of the branch pipe. The stub-on connection is not the same construction as a

Piping QA

stub-in connection - but the resulting geometry is the same as a stub-on. Stub-on connections are generally 90 degree, but can be other angles.

Branch table

28. Describe a stub-in connection and when it is used?

Fluor piping does not use the stub-in construction. A stub-in connection is the same as a stub-on connection as far as the resulting geometry and material goes, but the construction is different. The branch pipe may or may not be contoured to match the inside diameter of the header - if it is not, then it is a straight cut. The header will have a hole cut in it that nearly matches the outside diameter of the branch pipe. The branch pipe is inserted into the hole in the header and is connected via a fillet weld. Like the stub-on, the stub-in is generally 90 degree and other angles are possible.

Client request

29. Describe a reinforcing pad and when it is used?

Reinforcing pads are made from the same size, wall thickness and material as the pipe header to which they are welded.

Reinforcing pads are used at stub-on and stub-in branch connections and occasionally at support trunnions when specified by the stress sketch, if required per the line list or if required per the branch chart in the piping material specification.

30. What document (name and 5-diget number) does a piping designer refer to determine what branch connection to use?

Piping material specification

31. What are the two documents (not specifications) that will tell a piping designer when branch reinforcement is required?

Stress sketch

Line list

<Branch chart>

32. What is the pipe size range in which all flanges are standard?

24 inch and smaller

33. What is the pipe size range in which all flanges are not?

26 inch and larger

List the information to be placed on the isometric that will fully describe a non-standard flange and what is the reason we would include this information?

Reason for including the information.

To guarantee, without failure, the flanges are compatible.

Information to be placed on ISO.

Piping QA

ANSI number or other industry number (API, MSS)

Size

Rating

Facing

Outside diameter of flange

Bolt circle diameter

Bolt hole diameter

Number of bolt holes

Flange bore

Material

Bolt hole orientation

Flange thickness

35. What facing is required on a steel flange that will be bolted to a cast iron flange and why?

Flat Face

There is a risk of breaking the cast iron flange if it is bolted to a raised face steel flange.

36. What are two pressure ratings of cast iron flanges and what are the ratings of compatible steel flanges?

125# Cast iron to 150# steel,

250# cast iron to 300# steel.

37. How is cast iron flange attached to steel pipe?

The flange is threaded on.

38. What are two reasons for using lap joint construction?

To reduce the cost of components - a less expensive carbon steel flange may be used in lieu of a stainless steel flange.

Flange can be rotated to aid in bolthole alignment.

39. What fitting (not flange) must be used in lap joint construction and what are the names of two the types of these fittings?

Stub end <Lap joint stub end>

ANSI & MSS

40. What is the difference between a van stone flange and a slip on flange?

The shape of the contact point where the face of flange contacts the lip of the stub end is rounded on the van stone flange and is square on the slip on flange.

41. In lap joint construction, how many welds are on a slip flange?

Zero.

In lap joint construction, how many welds are on a van stone flange?

Zero.

Piping QA

43. List the types of steel flanges.

Weld neck

Slip on

Threaded

Socket welded

Van stone

Reducing

Expanding

Blind

<Lap joint>

<Orifice>

<Slip on reducing>

44. List the faces of steel flanges.

Raised face

Flat face

Ring joint

Tongue and groove

Male & Female

45. List the ratings of steel flanges.

150#

300#

400#

600#

900#

1500#

2500#

46. How are flange boltholes oriented on flanges on vertical line?

Boltholes straddle the north-south-east-west flange centerlines

47. How are flange boltholes oriented on flanges on horizontal line?

Boltholes straddle the vertical and horizontal flange centerlines

Valves are used for three basic flow functions (not control valves or pressure safety valves). List three functions and the type of valve used for each function.

Function

BLOCK THROTTLE CHECK

<Start / stop> <prevent back flow>

Type

GATE/BALL/PLUG/BUTTERFLY <needle> – BLOCK

GLOBE <plug or butterfly or needle> – THROTTLE

CHECK – CHECK

Piping QA

49. What are the two styles of butterfly valves in flanged piping and their associated type of bolt?

A. WAFER - STUD BOLT/MACHINE BOLT

B. LUG TYPE - CAP SCREW

50. What are the two main styles of check valves in flanged piping and their associated type of bolt?

A. SWING - STUD BOLT/MACHINE BOLT

B. WAFER/SPLIT DISC - STUD BOLT/MACHINE BOLT

51. Not using a ladder or platform, how is a valve operated that is:

Too high - CHAIN OPERATOR

Too low - EXTENSION STEM

52. What is the minimum clearance between the outside diameter of a valve hand wheel and the next obstruction?

Three inches

53. If a valve hand wheel projects into an aisle way, to what elevation must the bottom of the hand wheel be raised above HPFS (High Point Finished Surface) or platform?

6'-6" plus or minus 3" (6'-3" to 6'-9")

54. What manually operated item is added to a valve that is either to large or is to high a pressure to operate and how do you know it will be required (give the name of the specification)?

- A GEAR OPERATOR

- MATERIAL SPECIFICATION

55. If a pressure safety valve has a block vale upstream of it, what note must appear on the P&ID relating to this block valve and why?

CSO (car sealed open) or LO (locked open).

To help ensure that the valve is open during normal plant operation so that if a condition resulting in overpressurization occurs, the valve is open and the relief valve can function properly.

56. If a pressure safety valve downstream of it, what note must appear on the P&ID relating to this block valve and why?

CSO (car sealed open) or LO (locked open)

To help ensure that the valve is open during normal plant operation so that if a condition resulting in overpressurization occurs, the valve is open and the relief valve can function properly.

57. The piping downstream of a pressure safety valve that discharges to a closed system must be routed in a specific direction, what is this direction and why?

Routed in such a manner as to free drain into the collection header.

So no liquid can collect and possibly obstruct the free release of pressure.

Piping QA

58. If a pressure safety valve has a downstream block valve, excluding accessibility, how is the vale hand wheel to be oriented and why?

The handwheel is to be located within the lower 180 degrees - horizontal to horizontal. <horizontal or downward>

This is to prevent the disc falling into the port if the stem corrodes - thereby closing the valve and preventing the free release of pressure.

59. If a pressure safety valve has a rupture disc upstream, what is the purpose of the rupture disc?

The rupture disc isolates the relief valve from the potentially corrosive atmosphere of the system to be protected - protecting the stem from corrosion.

60. When a pressure safety valve discharges vertically to atmosphere, what must be added to the lowest part of the tail pipe, what size is it and why is it added?

A weep hole.

1/4" diameter

To drain the collection of rain water in the open tailpipe that if allowed to collect could obstruct the free release of pressure

61. What is the end preparation for the end tailpipe of a pressure safety valve discharging vertically to atmosphere and why?

Square cut/plain end

There is no need to bevel or 45-degree chamfer because it is unnecessary cost.

62. What is the formula for calculating the free standing (unguided) length of a tailpipe of a pressure safety valve discharging vertically to atmosphere?

1.67 x outside diameter (in inches) of the Tail Pipe = the height in feet.

63. If a pressure safety valve has a small, valved and plugged connection in the area between the block valve and the pressure safety valve, describe the purpose and operation of this valve.

For bleeding pressure and venting any trapped commodity so, the relief valve can be safely removed for maintenance.

64. Per Fluor Daniel Standard, what is the rule for establishing the height of a tailpipe of a pressure safety valve that discharges to atmosphere?

The top of a tailpipe discharging to atmosphere must be a minimum of 8'-0" above any platform within a 25'-0" radius of the tailpipe.

65. The spring on a pressure safety valve must be oriented in which direction and why?

Vertically upward.

To keep the spring out of any liquid that could corrode the spring.

Piping QA

66. Cooling water piping at the channel side of a shell and tube heat exchanger that is located outside in the sunlight will typically have a THERMAL RELIEF VALVE located between the exchanger nozzle and the block valve. Why is this done?

To protect the tubes of the exchanger from splitting due to overpressurization of the system when the valves upstream and downstream of the exchanger are closed. Sunlight can cause a temperature rise of the trapped liquid, causing a rise in pressure.

67. What is the most common body style for control valves?

Globe

68. In a control valve manifold with block valves upstream and downstream of the control valve, what is placed between the upstream block valve and the control valve and what is its purpose?

3/4" valved & plugged bleed valve.

To drain and depressurize the volume of trapped liquid for the safe removal of the control valve for maintenance.

69. If a control valve manifold has a bypass line what is the distance between the bypass valve and the main line and why?

Minimum distance.

To prevent a dead leg in the bypass line.

70. What is the minimum clearance between the top of the diaphragm on a control valve and the nearest obstruction above it?

1’-0” (12 inches)

71. In a control valve manifold with upstream and down stream block valves

A. What is the breakout spool piece for?

Easy removal of the control valve.

B. What is the preferred configuration of the breakout spool piece and why?

Preferred configuration is with an elbow.

It is easier to remove than a straight spool piece that requires a flange spreader. The "l" shape allows gravity to aid in its removal.

72. Who determines the size of the control valve?

Process

73. Who determines the size of the bypass valve?

Process

Who determines the upstream and downstream block valves?

Process

Piping QA

75. If you are establishing the overall length of a control valve main fold for allocation of space and you do not have a vendor drawing giving the face to face dimension of the control valve, what valve will you use as a substitute face to face dimension (assume the control valve is 6”-3003RF)?

A 6"-300# GLOBE VALVE OR PIPING PRACTICE 000 250 2701

<17 ½ inches>

76. When a control valve and its downstream block valve are the same size and rating, they can be bolted together. What possible problem can occur when these two valves are bolted together?

The handwheel of the block valve may interfere with the topworks of the control valve.

Also give me two solutions that could correct the problem.

If the boltholes permit - rotate the block valve so the interference is gone.

Add two flanges back to back, and, if necessary add a spool piece to give the necessary clearances.

<place valve in the vertical>

77. There are three things that establish the height of a valued drain (bottom of drain top of finished surface). One thing that sets this height is Fluor Daniel standard (6”), what are two others?

Clearance for rodding out the drain.

Clearance required for the addition of a bucket to catch the liquid.

78. What are two industry terms when a threaded connection is also welded?

Seal welding

Back welding

79. What must be used on a threaded connection if it is to receive the weld referred to in question 69, and why should it not be used?

Thread compound or "pipe dope."

If thread compound/pipe dope is present and the connection is to be seal welded, the heat could cause a small explosion, injuring the welder.

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