This article is about Upper Tray Leak Test Procedure for Distillation Towers and Columns in pants and refineries. Here also discussed about what is basically function of Distillation column or tower in refinery.
Upper Tray Leak Test Procedure for Distillation Columns
First need to understand what is Distillation Column and Towers in refinery and plants.
What is Distillation Column and Towers?
A tower in a refinery typically refers to a tall vertical vessel used for separating and purifying different components of crude oil or other hydrocarbon feedstocks. These towers are also known as distillation columns or fractionation towers.
In a refinery, crude oil is first processed in a distillation column to separate it into various components based on their boiling points. The crude oil is heated and vaporized in the bottom of the column, and the vapors rise up the column, where they are separated into different fractions based on their boiling points. The heavier fractions with higher boiling points condense and are drawn off at the bottom of the column, while the lighter fractions with lower boiling points are drawn off from the top of the column.
Distillation columns can be quite tall, with some towers in large refineries reaching heights of over 100 meters. The height of the tower allows for greater separation of the different components of the crude oil, as the heavier fractions have more time to condense and be drawn off at the bottom of the column, while the lighter fractions rise higher up the column before being drawn off at the top.
This article gives detailed information regarding the Upper Tray leak test that must be performed after Upper Tray installation for towers in refinery. These towers are also known as distillation columns or fractionation towers. This topic is very useful for mechanical and process engineers who are working in Plants and refineries or in future want to be work.
Safety Precautions:
Personal protective equipment required (gloves, long sleeve working suit, protection glasses etc…). During the leak test no entry inside the top head is permitted if the adsorbent tower pressure is higher than 0.05 barg.
Manpower:
Following manpower is required to perform upper leak test in Distillation Column.
• 1 Supervisor,
• 3 helpers for checking of leaks
• 1 welder and 1 helper for repairing ifrequired
Upper Tray Leak Test Procedure
Upper tray and piping manifold leak tests
► Those tests have to be perfonned with dry air.
Note: This test is performed before installation of the equilibrium device. The flange of the equilibrium
device connection to the upper tray is kept blind flanged.
Figure 1: Upper tray and piping manifold leak test
Vessel pressurization and mechanical resistance of the upper tray
► Check the equilibrium device nozzle is blind.
► Manhole is kept open.
► Install a temporary blind flange equipped with an accurate pressure gauge on the pumparound inlet.
► During this step no entry inside the vessel is allowed.
► Pressurize bottom head from the top line under dry air at 0.3 bar g. The whole vessel including top head piping manifold will be air tested except the top head. Note it will take several hours to pressurize and depressurize the adsorber. Therefore this test will have to continue day and night.
► Carefully watch for any leakage around the pressurizing system and the temporary blinds installed before the test. If pressure cannot hold, then one will have to check all Ex/Ra (11 flanges), all D/F flanges (11 flanges), the 3 flanges for TW, flanges for sieve sampling, flanges for dump nozzles, all flanges at the bottom of the relevant adsorber, etc …
► When all leakages from flanges have been eliminated, hold the pressure during 4 hours. If the pressure decreases quickly, this would indicate a large leak on the upper tray (on the seal plates above or on one of the welding/flanged connection on the top tray piping).
► Depressurize the vessel from the bottom down to 0.05 bar g using the outlet PIA nozzle (1%%” piping on the blind flange).
► Visually verify the mechanical integrity of the different pieces of the tray and the piping. If no damage / deformation are found on the upper tray, the mechanical test is successfully passed.
Upper Tray Leak test
► Depressurise the vessel down to 0.1 bar g and hold the pressure during 2 hours. If pressure loss is below 0.01 bar/h over 2h, the leak test is successfully passed.
► Then decrease the pressure down to 0.05 bar g and visually verify the mechanical integrity of the
different pieces of the tray.
► Then, using soapy water, check for any seal welding or flanged connection leak.
► Fully depressurize and repair all identified leakages.
► Pressurize back the adsorber from the top line to check the repair.
► Perform these steps until the leak test is fully satisfactory (pressure loss is lower than 0.01 bar/h over 2 hours) and no more leaks are found.
► When leak test is satisfactoryly passed, proceed with next steps of upper tray installation procedure.
MATERIAL BASKET
NOTE:
1. ALL DIMENSION UNITS ARE IN MILLIMETER U.N.O.
2. USE FLOOR BASE= L 50x50x6 WITH PLATE 6MM THICK
3. MATERIAL BASKET = 1000x1000x1200
4. MANBASKET HEIGHT= 1200MM
5. LIFTING LUG 12MMt PLATE
6. ALL CONNECTION ARE WELDED WITH 6MM SIZE OF WELD FILLET TYPE.
7. SWL= 300KG
CIRCULAR MANBASKET
NOTE:
1. ALL DIMENSION UNITS ARE IN MILLIMETER U.N.O.
2. USE FLOOR BASE= L 65x65x6 WITH PLATE 10MM THICK
3. MANBASKET DIAMETER = 1000MM
4. MANBASKET HEIGHT = 2400MM
5. PIPE = 48.30MM, 3.2MMT
6. LIFTING LUG 12MMt PLATE
7. ALL CONNECTION ARE WELDED WITH 6MM SIZE OF WELD FILLET TYPE.
8. SWL = 500KG
UPPER TRAY INSTALLATION PROCEDURE | Tower Internals in Plants & Refinery
LOWER TRAY INSTALLATION SEQUENCE | Tower Internals in Plants & Refinery
GENERAL INSTALLATION NOTES ABOUT TRAY ASSEMBLY IN TOWER