Sunday, May 6, 2012

Design Consideration for Tank Farm

Tank Foundations

Foundations made by others shall be checked for uniform slope and levels for our acceptance. Reference of North and East markings or 00 orientation marking on the foundation has to be furnished by the client.

Sump pit on the foundation must be given prior to the commence-ment of the Bottom laying.

Base Plate Laying

The annular plates will be laid first and then the sketch plates and full plates will be laid with sequences mentioned in the drawing; minimum lap for any two plates will be 30mm. temporary tack welding will be done during the time of laying.

Base Plate Welding

The annular butt joints will be welded first. Subsequently every alternate short seam will be fitted and welded and at the same time nearest short seams will be freed from tack welds. The same procedure will be repeated for long seam welding. Temporary erection cleats and jigs/fixtures will be used for laying and avoiding distortion during the time of welding.

Shell Erection

After grinding off the weld reinforcement on the top the of annular joints where the shell will rest and the vacuum box testing of this portion, erection of shell will commence subsequent to marking the circle to tank inner radius on the tank base.First shell course plates will be rested on the mark-ings by providing small cleats on both sides of the shell plates on the tank base. For maintaining the gap for the ver-tical joints, spacers will be inserted in between the two plate edges. After tack welding the vertical joints, plumbing and gauging will be done prior to the welding of vertical joints. Temporary strong backs will be provided during the time of welding in order to check peaking of joints.

After completing the vertical welding from one side, the shell will be back chipped before weld is deposited from the other side. Second shell course erection will then be done, and the second shell plates will be rested on the first shell course with the help of spacers and wedges. Minimum two numbers of erection channels will be wedged per plate erected, with lower course of plate, for stability and safety.

For the second course vertical joints, fitting and welding will be done as said for the first course. After completing the ver-tical welding, horizontal joint set up and plumbing will be done prior to welding the same. Sequence of welding for the horizon-tal joints will be same as vertical welding.

For outside welding on the shell, welder’s trolley will be used and for inside, scaffolding will be provided for erection and welding purpose.

In the same manner, subsequent shell courses will be erected and welded. To safeguard erected tank plates, guy wire supports will be provided from plates to the channels anchored in ground.

After welding the last horizontal joint, the curb angle will be fitted and welded. Shell to bottom joint can be fitted before or after fitting the curb angle. After welding the curb angle, final plumb check will be done in accordance with the design code and also peaking and banding check for the shell joints will be done. Identification marks for welder and weld joints shall be marked on the tank by using paint or metallic marker simultaneously during fit up and welding.

Vacuum Box Test and Radiography

After all welding work on the tank base and shell vertical/horizontal joints, shell to bottom and curb angle to shell joints are welded, the tank base butt/lap joints will be vacuum box tested. Radiography of vertical/horizontal welds will proceed as erection and welding work progresses.

Roof Structure and Roof Plate Erection

The roof structures will then be erected and welded. After inspection of the same, the roof plates will be laid maintaining a minimum lap of 25mm . The sequence of welding of short and long seams for the roof plates will be the same as base plates. After all seams are welded, the roof peripheral joint with the curb angle will be set up and welded.

Tank Appurtenances

Installation and welding of tank fittings (on shell and root) and stairway will then be taken up as per orientation given in the drawings. The compensating pads given for openings shall be air tested for leakage as per design code.

Tank Cleaning

After all erection and welding work is over, the tank interior shall be cleaned by removing and grinding off all tacks and other fixtures. The tank shell openings shall then be blanked off preparatory to hydro-test.

Tank Testing

Prior to hydro-test, foundation levels will be taken by the customer with reference to the benchmark. After inspection of the tank and getting approval from the customer, water filling into the tank will commence. 24-hour interval shall be given after filling the water to ¼ full; ½ full and ¾ full and comparing of foundation levels will be done at the above-mentioned intervals.

After filling the tank shell up to the top, the tank will be allowed to settle for 48 hours. Prior to draining the water, final levels will be taken. The roof test will be done in accordance with the code prior to draining the water. During the time of filling and draining water, all roof openings will be kept open to avoid damage to the tank.

Storage of Petroleum Products

Why it so important?

General statutory approval of plan and installation for any petroleum/chemical plant.

1. Chief Controller of Explosive (CCOE) 

2. Chief Inspector of Boiler  
3. Chief Inspector of Factories.

CCOE is the enforcing agency for

A. Petroleum act 1934, petroleum rules 1976.

B. Gas cylinders rules 1981 & static and mobile pressure vessels (SMPV) (Unfired) Rules 1981.

When license register form CCOE :

A. Under petroleum act : License register to storage/Transport petroleum of :

B. Under Gas Cylinder rules :

B1. 1. LPG 100 Kg at a time

2. Flammable but non toxic gas Number of cylinders > 15 or Qty. 125 Kg.

3. Non Flammable and non Toxic > 50 cylinders

4. Toxic Gas > 5 cylinders

5. Acetylene gas > 15 Cylinders.

B 2. Under Compress

Compress Gas > 1.0 M3 water capacity

Definition of Compressed gas : Any permanent gas , liquefiable gas or gas dissolved in liquid under pressure the gas mixture which in a closed pressure vessel excurses process.

• 1.5 atm. g @ 15 0 c
• or > 2.0 atm g @ 50 0c
• or both

How license granted for storage of petroleum :

Following are required under petroleum act :

a) Letter indicating purpose of storage of petroleum product & nature of business

b) Piping cum equipment layout plans to scale

c) Plot plan indicating premises to be licensed with boundary indicated red and indicating area within 100M from edge of storage tank / unloading station.

d) Fire protection system/hydrant.

e) Equipment specification

f) Scrutiny fee.

Above ‘b’ Points to be Indicated :

i) Distance between storage tank and storage tank to fencing.

ii) Dyked area and volume of each dyked area minimum Dyked HT. Class c = 1.o M.

iii) Tank fitted with vent pipe to Atm. fitted with non corrodible wire goal.

iv) Protected area is surrounded by walls.

v) Electrical insulation on cables and motor data sheet for pumps.

Process design of Petroleum storage facility

1) Kg/hr required and hrs/day.

2) Find availability data for storage capacity.

3) Total storage tank capacity to be finalized.

As example

Furnace oil required for boiler firing

Boiler 100 TPH 10 Kg /cm2 g Sat.

Q 100 x 1000 x 600 Kcal/hr

Oil Required = 93/MITSDE

Say 15 days storage

8 hrs unloading time, say actual 4 hrs. ( 50% time for fixing, measuring ) 

Say 2 unloading stations as capacity 1 + 1.

Provide 2w + 1s 22m3 /nv ~ 30mcc pumps.

6) Transfer pumps :

required pumps , head based on final user.

Get Notified for new Tutorials:
*Check your email to confirm your subscription*

1 comment :

  1. Hi Mr. Ankit I was outstation for more than a month, its nice to see u writing about tank farm. I very frequently visit ur site as find it informative. Thanks Dude keep doing the good job.



© 2011 PIPING GUIDE - Designed by Ankit | ToS | Privacy Policy | Sitemap

About Us | Contact Us | Write For Us