Anchor Spacing API RP4G
Anchor spacing directly affects the stabilization of the rig or tower
When purchasing a new Rig, the rig manufacturer has a plate on either the carrier or the bottom of the mast with recommended Anchor spacing’s which are typically either 180 foot square or 150 foot square. Unfortunately the only areas you are going to find locations big enough to accommodate these patterns are in Texas, Louisiana, and Wyoming to name a few. California along with a handful or so of other states build much smaller drill sites. In Response to this, a committee was formed in the early 1980’s to address the issue of stabilizing the rigs on smaller locations. The committee consisted of Professional Structural Engineers, Oil Industry Representatives, Rig company Representatives to name a few. What was agreed upon between all parties and accepted by the rig manufactures was that on locations that would not accommodate the larger patterns that it would be acceptable to use the API RP4G pattern if the anchors used were installed and tested to meet the stresses of the given pattern.