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Drill string and volumesMetric units Unit converter

Hoisting system: line tension and derrick load

Fast-line and dead-line tension, derrick load and the rope breaking strength needed to lift the string on n lines, allowing for the efficiency of the block and tackle.

Formula
F_f = W / (n · E); F_d = W / nF_der = W + F_f + F_dF_br = SF · F_fE = (K^n − 1) / (K^n · n · (K − 1)), K = 1.04

Static calculation for hoisting at constant speed; acceleration, braking and working the pipe increase the loads. The efficiencies in the hint and the typical values follow API RP 9B for roller-bearing sheaves (K = 1.04 per sheave) and match the table of Bourgeois et al.; for plain bearings K = 1.09. The derrick load is the hook load plus the tensions of both line ends.

Source: API RP 9B (fast-line tension, sheave efficiency, design factors); Bourgeois et al., Applied Drilling Engineering (SPE, 1986), ch. 1; Kazakhstan industrial safety rules (order No. 355), item 831

Inputs

You can change a field's unit: the value is converted to the formula's units automatically.

W
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Buoyed string weight plus travelling block, hook and top drive.

n
E

Roller-bearing sheaves: 0.907 (4 lines), 0.874 (6), 0.842 (8), 0.811 (10), 0.782 (12), 0.755 (14).

SF

API RP 9B: at least 3 for drilling and tripping, 2 for running casing and pulling on stuck pipe; at least 2 for well servicing hoists (Kazakhstan rules, item 831).

Unit converter for this formulaForce and load · Fraction and percent
Metric
  • kN1
  • N1,000
  • MN0.001
  • tf0.101972
  • kgf101.972
US field units
  • lbf224.809
  • klbf (kip)0.224809
All units →
Result
F_f — Fast-line tension
Fill in all fields
  • F_d — Dead-line tension
    –
  • F_der — Derrick load
    –
  • F_br — Required rope breaking strength
    –

More in Drill string and volumes

Pipe capacity and displacement

Internal volume per metre and for the whole string, metal (open-end) and closed-end displacement — for the trip sheet: hole fill when pulling and returns when running in.

Annular capacity and volume

Volume per metre and over an interval of the annulus between the hole (or casing) and the pipe.

String weight in mud and hook load

String weight in air and in mud (buoyancy factor) for one or two pipe sections, and the hook load including the travelling block and top drive.

Results are engineering estimates from standard formulas; for design decisions check them against the codes, project documents and specialists' calculations. The formulas carried over from the original set are unchanged, and their errors are described in the notes.