API 650 ORGANIZATION – SECTION 1: SCOPE & SECTION 4: MATERIALS

On the previous share, (please click HERE to read) we already discuss briefly about API 650 – Organization, which consist of:

• Section 1 – Scope
• Section 4 – Materials
• Section 5 – Design
• Section 6 – Fabrication
• Section 7 – Erection
• Section 8 – Inspection
• Section 9 – Welding
• Section 10 – Markings

So, for today, we will discuss about Section 1 – Scope and Section 4 – Materials. Lets read!

SECTION 1 – SCOPE

This standard covers:

1. Material, design, fabrication, erection and testing requirements for vertical, cylindrical, aboveground, closed and open top, welded steel storage tank in various sizes and capacities for internal pressures approximating atmospheric pressure.
2. Only tanks whose entire bottom is uniformly supported and only tanks in non-refrigerated service that have a maximum operating temperature of 90⁰ C (200⁰ F).

SECTION 4 – MATERIALS

General material requirements

• Acceptable standards for tank steel plate requirements.

-ASTM (Section 4.2.2)

-CSA (Section 4.2.3)

-ISO (Section 4.2.4)

-National Standard (Section 4.2.5)

• Plate for shells, roofs and bottoms may be on an edge-thickness basis or on a weight [kg / m2 (lb / ft2)] basis. Example: 3/16″ plate (0.1875″ or 7.65 lbs.) or 1/4″ plate (0.250″ or 10.4 lbs.), etc.
• Whether an edge-thickness or a weight basis is used, an under run of not more than 0.3 mm (0.01″)” from the computed design thickness or the minimum permitted thickness is acceptable.

MATERIAL SELECTION

API 650 allows specific materials that can be used.

These materials need to have adequate “toughness”

HOW TO GET TOUGHNESS?:

1. Find material group (Table 4-4b)
2. Determine MDMT = A (Fig 4-1b)
3. Determine lowest one day temperature (Fig 4-2 + 15 degree Fahrenheit (3.4) = B
4. If B > A, then build the tank. Otherwise, do impact test or choose another material.

EXERCISE

1. Bottom course of a tank shell is 22 mm in thickness and is made from A-516 gr. 65. Tank is to be built in Denver, USA.
2. A-283 Gr.C with thickness 30 mm. Tank is to be built in Vancouver, Canada.

To be continued on the next sharing.

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