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Design Criteria for Horizontal Equipment
Design Criteria for Horizontal Equipment

1. Wind Load:

  a). Basic diameter = diameter O.D. + 2 ( shell thickness + insulation).
    effective projected area = height x I.F. x basic diameter.

  b). Intensification Factor (I.F.):

    Diameter <= 760 mm, I.F. = 1.50
    Diameter 900 to 1350 mm, I.F. = 1.40
    Diameter 1370 to 1960 mm, I.F. = 1.30
    Diameter 1980 to 2570 mm, I.F. = 1.20
    Diameter >= 2590 mm, I.F. = 1.18

  c). The vessel saddle to pier connection shall be considered fixed for transverse loads.

  d). Longitudinal winds shall be resisted by the fixed end pier only.

  e). The force required to remove tubes from heat exchanger shall be 100% of bundle weight, but >= 19kN.

2. Load Combinations:

  Empty Load (or Erection Load) + Wind (Seismic)
  Operating Load + Temperature + Live Load
  Operating Load + Wind (Seismic)
  Operating Load + Temperature + Wind (Seismic)
  Operating Load + Temperature + Live Load + Wind (Seismic)
  Test Load
  Test + 0.5 Wind (Seismic)
  Empty Load + Bundle Pull Load (applies to supports only)

3. Sliding Plates:

  Teflon plates are normally 25 mm smaller than the length and width of the saddle base leaving 12.5 mm margin all around.

  Vessel support and top Teflon plate shall have horizontal slotted holes to allow movement due to expansion and contraction.

4. Pier Design:

  Pier shall be designed as cantilever columns, k = 2.0.

  Pier width >= 10% of height or 300 mm, minimum concrete cover for anchor bolts shall be 100 mm.

  Normally, pier dimensions = saddle support base plate size + 100 mm.

  A double tie shall be placed at top of piers spacing 50mm and 125mm below top of concrete.

  Minimum vertical reinforcement = 0.25% times gross section area.

5. Footing Design:

  The common footing is used for pier spacing <= 4m.
  Use two separate spread footing when pier spacing > 4m, tie beam may be used.

6. Normally, the stability ratio is >= 1.5 for sliding and overturning.

7. Soil Bearing:

    e <= a/6     B.P.max = P/a [1 + 6e/a]         B.P.min = P/a [1 - 6e/a]
    e > a/6     B.P. = 2P / [3a(a/2 - e)]

8. Period for Seismic Design:

    Reference: ASCE Guilde for Seismic Evaluation and Design of Petrochemical Facilities 4.A-6

  T = 2 π [y / (12 g)]0.5

    y - horizontal displacement at the top of supporting pier (in.)
    g - 32.2 (ft./sec2)
    T - period (sec.)

   y = W. L3/ (3 E. I)

    W - vessel operating weight (lbs)
    L - Distance from the top of the foundation to the bottom of the saddle for longitudinal period determination
         and from the top of foundation to the vessel centerline for transverse period determination (in.)
    E - modulus of elasticity (psi)
    I - moment of intertia of one pier (in.4)