Some have asked questions such as: "What is Balance of Plant?"; "What is Offsites?" What is OSBL?" and "What needs to be considered when a project includes Offsites."
The term Offsites is a general term and does not mean the same for every project or every plant. A project may include extensive tankage for feed storage along with tankage for in-process product, intermediate product, run-down tankage, slops and finished product tankage. Another project may include none of this because they already exist. The point here is just because you are told that the project includes "Offsites" you need to ask a lot of questions to determine exactly what they mean and what will be required.
The purpose of this document is to aid in answering this type of question. This document will not tell you how to design the Offsites or design any of the individual sub-items or equipment found on this list. That design guidance should properly be left up to you, your supervisors and your management. I do however intend to start a listing of major elements along with some minor key issues that should be considered.
I invite others to submit their own thoughts and comments to add to and improve this list.
Offsite -- In a process plant (Refinery, Chemical, Petrochemical, Power, etc.), any supporting facility that is not a direct part of the primary or secondary process reaction train or utility block. Offsites are also called OSBL.
Onsite - Any single or collection of inter-related and inter-connected process equipment that performs an integrated process function. Typically any Onsite Unit could be made to function independently of another Onsite Unit. Onsite Units are also called ISBL.
Utility Block - A single or multiple grouping of facilities that generate the support services required by the Onsite Process units to function. This normally includes: Steam Generation, Plant Air, Instrument Air, Decimalized Water, Plant Water, etc.
Balance of Plant - This is another term for Offsites and/or anything else other than the Onsite Units or the Utility Block.
Property Line -- A Property Line is the recorded boundary of a plot of land. (2) Defines the separation between what is recognized legally as Owner's land and non-Owner's or other land.
On Property -- All land and or water inside the Property line shown on the property map or deed.
Off Property - Off property is any land (or water) outside of the Property line shown on the property map or deed.
Right of Way (ROW) -- Any land (On Property or Off Property) set aside and designated for a specific use or purpose. A Right-of-Way within a piece of property may also be designated for use by someone other than the property owner.
Setback or Setback Line -- A line established by law, deed restriction, or custom, fixing the minimum distance from the property line of the exterior face of buildings, walls and any other construction form; s street, road, or highway right-of-way line (3). Setback is a clear area normally at the boundary of a piece of property with conditions and restrictions for building or use.
Easements -- A vested or acquired right to use land other than as a tenant, for a specific purpose; such right being held by someone other than the owner who holds the title to the land (2). An easement is typically a strip of land within which overhead power lines or underground pipes are run.
- Minimum distance between loading "Spots"
Jaydeep R. Chaudhary is a piping designer with 4+ years of experience with oil & gas projects working with Hyundai Heavy Industries, Seoul South Korea.
Anita R. Legvold is a Piping Design Engineer with more than 35 years experience covering process plant engineering, design, and field activities. She is now semi-retired and lives in Florida, USA.