# 8.2.8.1.1 Plungers Not Subject to Eccentric Loading

** **

*(a)* Where the slenderness ratio of the plunger is less than 120

*(SI Units)*

*(Imperial Units)*

*(b)* Where the slenderness ratio of the plunger is greater than 120

*(SI Units)*

*(Imperial Units)*

Formulas are for steel where

A |
= | net sectional area of plunger (area of metal), m^{2} (in.^{2}) |

L |
= | maximum free length of plunger, mm (in.). Where a plunger-follower guide conforming to 3.18.2.7 is used, L shall be taken as one-half the amount that the free length would be if no follower guide were provided. |

R |
= | radius of gyration of plunger section, mm (in.) |

W |
= | allowable gross weight to be sustained by the plunger, N (lbf). Where a counterweight is provided, the weight of the counterweight plus the unbalanced weight of the counterweight ropes shall be permitted to be deducted in determining W. In determining W, one-half of the weight of the plunger shall be included except where a plunger-follower guide conforming to 3.18.2.7 is used, in which case, three-fourths of the plunger weight shall be included. |

W/A |
= | fiber stress, kPa (psi] |

NOTE [8.2.8.1.1(a) and 8.2.8.1.1(b)]: Figure 8.2.8.1.1 has been calculated from the formulas given in 8.2.8.1.1 for the more usual pipe sizes and pipe schedules and indicates allowable gross loads directly.

*(c)* Plungers having a free length of 7.6 m (25 ft) or less shall be permitted to be accepted without further examination for strength and elastic stability, provided all of the following conditions exist:

*(1)* the working pressure is 2070 kPa (300 psi) or less

*(2)* the plunger is 100 mm (4 in.) nominal pipe size or larger

*(3)* pipe not lighter than Schedule 40 is used, and not more than 1.6 mm (0.063 in.) of metal has been removed from the wall thickness in machining

*(d) Plungers With Varying Cross Section.* For plungers with varying cross section, the stress shall be calculated for a factor of safety of at least 3 using accepted methods for elastic stability.

Figure 8.2.8.1.1 Allowable Gross Loads

**Figure 8.2.8.1.1 Allowable Gross Loads (Cont'd)**

GENERAL NOTES:

- Curves are based on the removal of not more than 1.5 mm (0.0625 in.) from the wall thickness in machining.
- Curves stop at 18 m (59 ft) for convenience only. For plunger sizes or lengths not shown on this chart, see the applicable formula in 8.2.8.1.1,

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