Common question welding storage (part 2)
Common question welding storage API 650 (part 2)
Question: Is the conversion of design wind velocity of 100 mph to a peak 3 second wind gust 50 m/s giving design wind pressure of 31 psf or 1.485 kPa correct?
Answer: The American Petroleum Institute does not approve, recommend, or endorse any proprietary or specific design; nor does it limit the method of design or form of construction that might be used to conform to an API Standard. Therefore, we cannot act on your inquiry. We suggest that you review the notes to Sections 3.9.6.1 and 3.9.7.1.Question: Reference API 650 Section 3.9.6.1, is it permissible to use a double wind girder in lieu of a top wind girder on an open top tank?
Answer: The top wind girder must meet the requirements of API 650 Section 3.9.6. API does not restrict the details of construction.
Question: Must corrosion allowance be subtracted from t in the formula of 3.9.7.1 and 3.9.7.2?
Answer: No
Question: Does API 650 require the tank supplier to meet the intermediate wind girder requirements of Section 3.9.7 for all fixed roof tanks?
Answer: Yes
Question: If more than one intermediate wind girder is required, is the section modulus of the second intermediate wind girder based on the height between the second intermediate wind girder and the top wind girder, or should H1 be based on 1/2 the distance between adjacent wind girders/stiffeners where the bottom plate counts as the bottom stiffener?
Answer: To determine the section modulus of the second intermediate wind girder, first determine the transformed shell height equal to the distance between the fist wind girder and the top wind girder. Subtract this value from the total transformed shell height determined in Section 3.9.7.2. The remaining shell is then transposed to an actual shell height and this value is used for H1 in the formula in Section 3.9.7.6.
Question: In Section 3.9.7.1, should footnote (a) be referred to when analyzing wind velocities other than 100 mph?
Answer: Yes
Question: Does Section 3.9.6 apply only to open top tanks and Appendix G tanks?
Answer: Yes
Question: Is it correct to consider length of shell 1.47×(D×t)0.5 specified in 3.9.7.6.2 on each side of the shell-ring attachment, resulting a total shell length of [2×1.47×(D×t)0.5 + (width of wind girder in contact with shell)]?
Answer: Yes
Question: If the corrosion allowance plus the calculated thickness is less than 3/16 in. thick, must the corrosion allowance be added to the 3/16 in. minimum nominal roof thickness?
Answer: No
Question : Does a 2% slope for a supported cone roof tank meet the requirements of API 650?
Answer : No
Question : When designing a cone roof based on the formulas in API 650, are factors of safety included in the rules of API 650 or must they be considered separately by the tank designer?
Answer : The necessary and appropriate factors of safety are included inherently in the design rules of API 650.
Question : Is welding of the main roof support members to the roof plates allowed by the standard?
Answer : No, see API 650, Section 3.10.2.3, that states that roof plates of supported cone roofs shall not be attached to the supporting members.
Question : How do you size an emergency vent for a sulfuric acid storage tank?
Answer : API can only provide interpretations of its standard and consider revisions based on new data or technology. API does not act as a consultant on specific engineering problems or on the general understanding or application of the standard.
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