API RP 2A - Pile Straightness 1

[keurtra]

Hi all,

I have a pile 19m length with 7 shells. Each shell is 2.75m high. Diameter 8m.

In the API RP 2A, it's written:
Straightness
The maximum allowable straightness deviation in any 3 m length shall be 3 mm. For length over 3 m,
the maximum deviation of the entire length may be computed by the following formula, not to exceed
10 mm in any 12 m length.
3 mm x (total length m.)/3 m

It means that for my 1st shell it will be 3mm.
But for the 2nd shell (5.5m high) we have to calculate with the formula the total length of my pile (19m) or by section?

-1st shell 2.75m high : 3mm
-2nd shell 5.5m high : 5.5mm
-3rd shell 8.25m high : 8.25mm
-4th shell 11m high : 11mm cause in any 12m length it will be 10mm.
-5th shell 13.75 high : ??? what will be the tolerance???

or

-1st shell 2.75m high : 3mm
-2nd shell 5.5m high : 19mm (formula with total length of my pile)
-3rd shell 8.25m high : 19mm(formula with total length of my pile)
-...

Many thanks if you could help me cause everybody has his own opinion on it.

Best regards

 

[OGMetEngr]

Once you exceed 3m the formula it gives you should be used. Also required is that any 12m length deviation should not be more than 10mm.

-1st shell 2.75m high : 3mm
-2nd shell 5.5m high : 5.5mm
-3rd shell 8.25m high : 8.25mm
-4th shell 11m high : 11mm (but must also meet 10mm when next 1m is included)
-5th shell 13.75m high : 13.75mm (and any 12m section with 10mm deviation max)
-6th shell 16.5m high : 16.5mm (and any 12m section with 10mm deviation max)
-7th shell 19.25m high : 19.25mm (and any 12m section with 10mm deviation max)

It gives the formula BUT not to exceed 10mm in ANY 12m length (emphasis added).

 

[keurtra]

Hi OGMetEngr,

Thanks for your answer. But for my pile, how I will calculate my verticality for each shell? My friends are saying that it's the staightness. Is that right?

Please find below the link of the verticality of my 4th shell using straightness formula:



If you could help me to have a better understanding of the verticality using the straightness.

Many thanks for your answers.

 

[Duwe6]

Verticality = deviation from a plumb-line = deviation from perpendicular to the earth's surface

Straightness = deviation from a line drawn from one end of the sheet to another.

Thus, a flat sheet laying on the truck can be straight, zero deviation from a line drawn from one end to the other. And that sheet is completely non-vertical. Straightness is for the material, verticality is for the as-driven condition. If the sheet is non-straight, it can never have good verticality. If a straight sheet is driven crooked, it cannot have good verticality.

 

[keurtra]

Many thanks for your replies

 

[r2d22]

Hi OGMetEngr,
And how would you interpret the following:
API RP 2A 11.1.5.b Jacket and Deck Section Columns states:
"The deviation from straightness of jacket columns should be less than 3/8 in. (10 mm). Such deviation should not be more than 1/8 in. (3 mm) in any 10 foot (3 m) increment of length."
It seems that for jacket legs the requirement is more conservative as straightness should be less than 10mm, for the entire length.
Supposse a jacket in 250ft water depth with legs 270ft long . The leg should have 10mm max deviation in the whole length while the pile that will be driven inside could have up to 82.2mm deviation?
Regards,