CONSTRUCTION STANDARD TANK HYDROLOADING PROCEDURE K20-2CS-BASE DATE: 01 APR 2003
ENGINEERING SERVICES BY KBR TECHNICAL SERVICES, INC.
PAGE 1 OF 3
Note: Before using on a project, BASE specs must be revised as a project spec with applicable project details.
TABLE OF CONTENTS Section 1. 1.1 1.2 1.3 1.4 2. 2.1 2.2 2.3 2.4 3.
Title Page No. GENERAL ......................................................................................................................................1 Scope..............................................................................................................................................1 Work To Be Performed ................... ............................ ................... ................... .................. ................... ................... ................... ................... ................ ................. ..............1 ....1 Industry Industr y Standards ................................. ................ ................. .................. ................. ................. ................. .................. ..1 Preparation Prepara tion for Hydroloading Hydroload ing................ ................................. ................. ................................. ................ ................. ................................... ................ ................... .....2 LOADING, RECORDING OF DATA, AND UNLOADING .............................................................2 Loading ................. ................. ................. ................. ................. ................. ..................... ................ 2 Recording and Monitoring of Data During Loading ................... ............................. ................... .................. ................... ................... ...............2 ......2 Unloading........................................................................................................................................3 Recording of Data During Unloading......................... Unloading.................................. .................. ................... ................... ................... ................... ................. .............3 .....3 REPORT OF DATA ........................................................................................................................3
1. GENERAL 1.1 Scope This standard establishes the procedure for hydroloading and settlement monitoring and recording during hydrotesting of designated tanks. 1.2 Work To Be Performed Performed 1.2.1 A survey monument shall be designated within within the site area for the hydroloading program. 1.2.2 The scope of hydroloading work consists of the following following as described in this standard: a.
Locating the the designated designated settlement monitoring points points in accordance with with Table Table 1.
b.
Installing temporary bench marks at tank locations.
c.
Installing and monitoring monitoring geotechnical geotechnical instrumentation instrumentation such as piezometers and inclinometers inclinometers at specified locations, if any.
d.
Filling the tanks with water.
e.
Reading, recording, plotting and reporting the settlement data.
f.
Emptying the tanks.
1.3 Industry Standards The following documents are referenced referenced herein and form part of the Order. Current editions of the industry standards including all mandatory addenda in effect at the time of the order shall apply unless otherwise indicated. AMERICAN PETROLEUM INSTITUTE (API) API 620, "Design and Construction Construction of Large, Welded, Low-Pressure Low-Pressure Storage Tanks" API 650, "Welded Steel Tanks for Oil Storage" Storage"
CONSTRUCTION STANDARD TANK HYDROLOADING PROCEDURE K20-2CS-BASE DATE: 01 APR 2003
PAGE 2 OF 3
ENGINEERING SERVICES BY KBR TECHNICAL SERVICES, INC.
Note: Before using on a project, BASE specs must be revised as a project spec with applicable project details.
1.4 Preparation for Hydroloading 1.4.1 A minimum of two (2) temporary bench marks per tank shall be established for the purpose of determining the elevations of settlement points. These bench marks shall be located a minimum distance of one (1) tank diameter from any of the tanks being hydroloaded. 1.4.2 Hydroloading shall not be initiated until adequate arrangements have been made for the disposal of water during tank unloading. 1.4.3 All roof nozzles, except roof manways, shall be kept open during tank filling with water and emptying. 1.4.4 Tank filling with water shall commence only after the tank bottom, attachment welding around reinforced openings and shell to bottom welds are inspected for leaks by the tank subcontractor in accordance with Paragraphs R 8.2 and R 9 of API 620 for ammonia storage tanks, and Paragraphs 5.3.4 and 5.3.5 of API 650 for all other tanks. 1.4.5 All tanks requiring interior lining or coating shall be hydroloaded/hydrotested prior to application of lining/coating. 2. LOADING, RECORDING OF DATA, AND UNLOADING 2.1 Loading 2.1.1 Tanks shall be vented to atmosphere while filling or emptying; See Paragraph 1.4.3. 2.1.2 Immediately before the actual filling of the tank, a zero reading of all settlement points shall be established. 2.1.3 Tanks supported on dense/hard sub-soils may be filled with water as rapidly as desired, provided the safety factor against ultimate bearing capacity is 2.5 or more. 2.1.4 For tanks supported on other sub-soils, tank loading shall be accomplished in stages as described below to ensure that tank foundations soils do not become o verstressed: a.
First stage:
Fill tank ft. ( mm) deep with water, or to the top of tank, whichever is less. Wait at least 1 week and until rate of tank settlement is less than 0.1 inch (2.5 mm) per 24 hour period.
b.
Second stage:
Fill tank ft. ( mm) deep with water, or to the top of tank, whichever is less. Wait at least 1 week and until rate of tank settlement is less than 0.1 inch (2.5 mm) per 24 hour period.
c.
Third stage:
Fill tank to the top and hold for at least 1 week.
2.1.5 After every loading stage of the tank filling, the tank shall be visually examined for tightness of welds in the shell, including corner welds between the shell and bottom, in accordance with API 650 or API 620 as applicable. 2.1.6 The rate of loading for each stage should be limited to 2 feet (610 mm) per day. 2.2 Recording and Monitoring of Data During Loading 2.2.1 For each stage of loading, settlement readings shall be taken at holding periods.
hour intervals during filling and the
2.2.2 Settlement readings shall be plotted, as the test progresses, with the x-axis indicating time and y-axis representing settlement values in inches. Each "set of readings" shall include one (1) elevation reading from each settlement point indicated in Table I.
CONSTRUCTION STANDARD TANK HYDROLOADING PROCEDURE K20-2CS-BASE DATE: 01 APR 2003
ENGINEERING SERVICES BY KBR TECHNICAL SERVICES, INC.
PAGE 3 OF 3
Note: Before using on a project, BASE specs must be revised as a project spec with applicable project details.
2.2.3 Settlement readings shall be closely monitored and the tank unloded at a safe rate if excessive uneven settlement is detected which could result in a foundation/tank stability failure. a.
During recording of settlement readings, if the rate of differential settlements between any two (2) points along the perimeter of the tank is over 0.25 inch (6.3 mm) per 6 hour period, it shall be considered excessive.
b.
Settlements exceeding the estimated settlements depicted in Table 1 shall be brought to attention for resolution.
2.3 Unloading 2.3.1 After completion of the final loading stage, water shall be emptied at a rate convenient for disposal. 2.3.2 During unloading the water discharge shall be sufficiently clear of tank foundation to avoid soil erosion. 2.3.3 Tanks shall be emptied through the lowest nozzle. The shell manhole shall not be opened until the water level is below its elevation. 2.4 Recording of Data During Unloading Four (4) sets of readings shall be taken and plotted for each tank unloading: a.
Immediately before unloading tank.
b.
Immediately after unloading tank.
c.
One (1) day after unloading tank.
d.
One (1) week after unloading tank.
3. REPORT OF DATA At the completion of each tank hydroloading, one (1) copy of data and charts shall be submitted. TABLE I SETTLEMENT DUE TO HYDROLOADING
TANK ITEM NO.
*
ESTIMATED SETTLEMENT AT PERIMETER inches (mm)
NUMBER OF MONITORING POINTS AT PERIMETER
AT CENTER
The number of monitoring points along the tank perimeter shall be 3, 6, and 8 for tank diameters up to 50 feet (15.2 m), 100 feet (30.5 m), and over 100 feet (30.5 m) respectively. Monitoring points shall be evenly spaced along the tank perimeter. A monitoring point shall be installed at the center of tanks, 50 feet (15.2 mm) in diameter or greater, where possible.
