8- Methods of Inspection

Question 1

Before entering or re-entering any tank, appropriate safety precautions are necessary. These precautions are discussed in detail in ,,,,,,,,

Answer 1

API 2015 and API 2016

Question 2

Prior to conducting internal or external inspection, the inspector should thoroughly review any available ,,,,,,

Answer 2

inspection records
previous problems and
recommendations noted

Question 3

In preparation for inspection, it is important that all personnel working in the area and any who may enter the area be informed that ,,,,,,,,

Answer 3

personnel will be working in the tank

Question 4

Anchor bolt nuts should be checked for a …….

Answer 4

snug fit to the anchor chair top plate

Question 5

For ground connection, . The

total resistance from tank to earth should …….

Answer 5

not exceed approximately 25 ohms.

Question 6

Corrosion under insulation (CUI) is most aggressive in temperature ranges between ,,,,,,,,

Answer 6

120 °F (49 °C) and 200 °F (93 °C)

Question 7

In obtaining shell thickness, special attention should

be given to the ,,,,,,,of uncoated shells of floating-roof tanks

Answer 7

upper 24 in. (61 cm)

Question 8

Modern ultrasonic ,,,,,, when properly calibrated, allow direct metal thickness readings to be taken through thinfilm coatings.

Answer 8

multi-echo thickness scopes

Question 9

If caustic or amine is stored in a tank, the tank should be checked for evidence of damage from caustic stress
corrosion cracking, sometimes referred to as ,,,,,,,,

Answer 9

caustic embrittlement

Question 10

On a fixed roof, planks long enough to span at least ,,,,,,,, should be laid and used as walkways

Answer 10

two roof rafters

Question 11

Electrical shunts, if present, should be checked to ensure adequate contact between the ,,,,,,,

Answer 11

floating roof and the shell

Question 12

Drainage systems on floating roofs should be inspected frequently for ,,,,,,

Answer 12

leakage or blockage

Question 13

,,,,,,, measurement equipment, which can provide accurate thickness through thin-film coatings, should be used wherever possible

Answer 13

Multi-echo ultrasonic

Question 14

When external piping inspection is specified, the soil around the pipe should be dug away for ,,,,,,,to allow for inspection, as soil corrosion may be especially severe at such points.

Answer 14

6 in. to 12 in. (150 mm to 300 mm)

Question 15

Coupons approximately ,,,,,,, in size can also be removed from the roof to check for under-side corrosion and rafter condition

Answer 15

12 in. × 12 in. (300 mm × 300 mm)

Question 16

although the best way to find leaks in the roof is with the ,,,,,, test discussed later in this document.

Answer 16

low-pressure air

Question 17

The drain lines, including the joints, can also be tested for any leak. The first stage is a test at about ,,,,,,, gauge pressure for approximately,,,,,,, to detect any leaks in the pipe, hose, or rigid joints. The pressure is then reduced to approximately ,,,,,, gauge for another ,,,, hour to test the tightness of the swing joints

Answer 17

30 lbf/in.2 (207 kPa) for 1/2 hour

5 lbf/in.2 (34.5 kPa) for 1/2 hour

Question 18

For tank bottom inspection, A minimum ,,,,,,,, halogen light is usually adequate

Answer 18

100-watt

Question 19

For tank bottom inspection, ,,,,,, are the most common but hybrid MFL/Eddy Current, ,,,,,,,,and well as ultrasonic based may also be used

Answer 19

Magnetic Flux leakage (MFL) scanners

Saturate Low frequency Eddy Current *SLOFEC)

Question 20

For tank hydro/leak tes, approximately ,,,,,, hours may be required for leaks to become evident

Answer 20

24 hours

Question 21

If water is not available and if the roof of the tank is reasonably air tight or can be made so, a carefully controlled air test using air pressure ,,,,,,,of water pressure may be applied.

Answer 21

not exceeding 2 in. (0.50 kPa)