VK Estimating Solutions

When estimating any oil & gas project, detailed piping estimate is one of the most time-consuming elements. Piping material take-offs can sometimes be in the form of several hundred or even thousands of line items, which an estimator takes weeks to estimate. Some companies have specific piping estimators for the job.

In all oil & gas projects, there are several pipes going in and out of the various equipment items helping the process and utility fluids to move around in the required direction and destination. This piping forms a major portion of the final plant and the cost estimate. There are several piping items such as: pipes, fittings of various kinds, flanges of various kinds, valves of various kinds, and the corresponding gaskets and fasteners. There could be several sizes and pressure ratings of the various piping items. And then there may also be various metallurgies involved. The material take-offs are generally done separately for various lines, which means, similar items could be repeated several times. The whole list is generally very long by the time it comes for estimating.

The piping estimator then tries to find the cost of individual line items from the in-house database and invariably takes a long time to find an exact match for the material, size and schedule of a specific piping item. If the company has previously used similar items in another recent project, then there might be a possibility of getting some in-house data, but even then, it might not be available for all items. The team might end up factoring those items from another nearby size and/or schedule. This whole process is very laborious. Even with databases and software, no company could have an exhaustive databank of prices of all possible piping items.

Depending on the budget and resources available, the team might decide to go out to the market to get recent prices for all the piping items, but even that takes a considerable amount of time.

Once this laborious process is completed, it becomes very difficult to review the overall estimated piping supply cost, as it is nearly impossible to go through each line item.

I am going to suggest a surprisingly simple method to help expedite the piping estimate and review process. For this, all piping items can be converted into weights and then multiplied with an average $/kg rate for the various types of piping items to arrive at a rough piping material supply estimate for comparison.

The table below offers indicative benchmark average $/kg rates for various carbon steel piping items (free estimating resource).

You can choose to use company specific rough $/kg rates for various piping items (instead of the above rates), which can be derived by using database information from past projects or previously obtained budget quotes. This is preparatory work, which can be done when there is less load on the estimating team. Similar rate tables can also be developed for other material such as stainless steel or duplex steel, or factors can be developed to modify the $/kg rates from carbon steel to the higher grades of material. (I will try to post indicative factors as a future blog.)

The weight tabulations for various piping items can be easily obtained from manufacturers of pipes, fittings, flanges and valves (I will share the piping weight tabulation in another post).

This method helps in quickly estimating a rough number for the material cost of all piping items. This can either be used when there is insufficient time or estimating resources to complete a more detailed estimate, or used by the reviewer of the estimate to cross-check the piping estimate done by others. If the weight tables are properly set up then this method can help arrive at a rough piping estimate within hours (or even minutes if the inputs are provided in specified formats), against weeks of work that is generally undertaken.

Note: The benchmark rates above are indicative only and intended to demonstrate how this method would work; they can help arrive at a reliable overall piping material estimate when time is short.