Horizontal Vessel Loading Calculation

Outline.

Horizontal Vessel Loading Calculation Procedure.

Conclusion.

Questions.

Step 1: Review of vessel drawing (Vendor Equipment Drawing).

Step 2: Verification of foundation location, elevation & external fittings loads.

Step 3: Description of Foundation Loads.

Step 4: Load combinations for foundation sizing / loads & Foundation design.

Step 5: Anchor Bolt Check.

Step 6: Pedestal Sizing and reinforcement.

Step 7: Slide plate.

Horizontal Vessel Loading Calculation

Procedure

Step 1: Review of Vessel Drawing (Vendor Equipment Drawing).

Engineer needs to review the drawings came from the vender, and check whether

you have all the following information:

1. Vessel Erection weight (Df).

2. Vessel Empty weight (De).

3. Vessel Operating weight (Do).

4. Vessel Hydro test weight (Dt).

5. Wind Shear and Moment in transverse direction.

6. Seismic Shear and Moment in transverse direction.

7. Vessel operating temperature and confirm with Mechanical discipline.

8. Total length of vessel and spacing of saddle supports.

9. Vessel Center of Gravity location with respect to saddle.

10. Anchor bolt location on fixed and sliding saddle.

11. Detail of equipment saddle (fixed and sliding).

Step 2: Verification of Foundation Location, Elevation & External Fittings Loads.

Engineer need to review Plot plan, Equipment location drawings and 3-D Models

and check whether you have all the following information:

1. Verify the area available for foundation.

2. Verify Foundation location and Elevation.

3. Location and size of Platforms around the vessel.

4. Locations of underground pipes.

5. Electrical and Instrument duct banks.

6. Locations and extent of adjacent foundations.

7. Verify the location and extent of new/existing foundations not shown in

3D model or plot plan.

Step 3: Description of Foundation Loads.

Vessel Erection weight (Df): Fabricated weight of the exchanger or vessel, generally taken

from vendor certified exchanger or vessel drawings.

Vessel Empty weight (De): Empty weight of the exchanger or vessel including all

attachments, trays, internals, bundle, insulation, fireproofing, agitators, piping, ladders,

platforms, etc.

Vessel Operating weight (Do): Empty dead load of the exchanger or vessel plus the

maximum weight of contents (including packing/catalyst) during normal operation.

Vessel Hydro test weight (Dt): Empty dead load of the vessel plus the weight of test

medium contained in the system.

Wind Shear and Moment (W): You will find this load data in vendor drawings. However,

you have to calculate this load based on project design basis.

Seismic Shear and Moment (E): During seismic load calculation, you need to consider the

pipes and platforms attached with the vessel.

Thermal Load (T): The thermal load is defined as the load which results from thermal

expansion or contraction of the vessel in the longitudinal direction.

Step 4: Load Combinations for Foundation Sizing / Loads & Foundation

Design.

You need to create the load combination per your project design criteria. However,

I have created this load combination based on ACI 318:

I. Load combination for Foundation sizing and Pile load calculation (un-factored

load calculation):

1. LC1: Do + Dp + T.

2. LC2: (De1 or De2) + Wind.

3. LC3: De2+ Seismic.

4. LC4: Do + Dp + Wind + T.

5. LC5: Do + Dp + Seismic + T.

6. LC6: Dt + 025*Wind.

Step 4: Load Combinations for Foundation Sizing / Loads & Foundation

design.

II. Load combination for Pedestal and Foundation design (factored load

calculation):

1. LC7: 1.4*(Do + T + Dp ).

2. LC8: 0.75 [1.4 De2 (or 1.4 De1)] +1.6 Wind.

3. LC9: 1.2 De2 +1.0 E.

4. LC10: 0.75 (1.4 Do +1.4 T + 1.4 Dp) +/- 1.6 Wind.

5. LC11: 1.2 (Do +T + Dp) + 1.0 E.

6. LC12: 0.75 (1.4 Dt) + 1.6 (0.25 W).

The weight of the foundation and of the soil on top of the foundation shall be

included as dead load in all of these load combinations.

Step 5: Anchor Bolt Check.

Maximum shear and tension on anchor bolt shall be calculated based on above

load combinations and shall be compared with project acceptable value.

Step 6: Pedestal Sizing & Reinforcement.

Unless controlled by other factors, the minimum pier dimensions in each direction should

equal to the dimensions of the base plate plus 100mm. Bars shall be sized in 50mm

increments. The minimum thickness of the bar should be approximately 10% of the bar

height, with a minimum of 250mm.

Bars size should be adjusted to ensure the factored vertical force on the bar does not

exceed the value of {0.1Agfc¢} (Refer ACI 318 section 10.3.5).

Bars should be designed as axially loaded cantilever flexural members.

When the size of the bar cannot be adjusted and the value of the axial load exceeds

{0.1Agfc¢}, the bars should be designed as compression members subjected to combined

flexure and compressive axial load.

Step 6: Pedestal Sizing & Reinforcement.

Shears on bars along both the longitudinal and transverse directions of the equipment

shall be checked per code requirements (refer ACI 318, Chapter 11).

Reinforcement should normally be arranged symmetrically. Both the fixed end and

sliding end bars shall be sized and reinforced identically.

A double tie shall be placed at the top of bars, spaced 50mm and 125mm below the

top of concrete (or below the bottom of grout), to protect the top of concrete bars against

cracking.

Step 7: Slide Plate.

Slide plates are placed at the sliding end bars to allow longitudinal movement of

vessels due to the thermal growth. Slide plates should be galvanized or painted to

prevent corrosion.

For large movements and/or heavy horizontal vessels, it may be necessary to use

slide plates with low coefficient of static friction, such as Lubrite, Teflon, etc.

To complete the foundation design, should be create the following calculation

sheets:

A calculation sheet for anchor bolt embedment length check (ex: ACI 318

appendix-D).

A calculation sheet for foundation sizing (considering soil bearing pressure,

Sliding, and overturning), and check with soil consultant for acceptable values.

A calculation sheet for foundation and pedestal reinforcement calculation per

your project design criteria.

Continue.

Now from above steps, should be learnt the following:

Different types of loads on foundation.

Different criteria for the pedestal sizing.

Maximum tension and shear force on each anchor bolt.

A sample load combinations.