---
title: What is a Full Opening Safety Valve (TIW valve)?
description: Full Opening Safety Valves (TIW valves) are an essential part of any drilling operation. TIW valves are ball valves designed for high-pressure conditions.
---
[PES | Blog ](https://eng-pes.com/blog)
# [What is a Full Opening Safety Valve (TIW valve)?](https://eng-pes.com/blog/what-is-a-full-opening-safety-valve-tiw-valve)
Written by [Admin](https://eng-pes.com/blog/author/admin) | Jul 10, 2026 12:41:02 PM
[There are two types of stabbing valves that must be prepared for well control: Full Opening Safety Valve (](https://www.3dexperienceworld.com/event/183e8765-55d4-4b1b-a738-755f833722e8/summary)[TIW](https://info.irefze.com/news/debunking-the-terminologies-of-ibops-and-fosvs) valve) and Inside [BOP ](https://www.keystoneenergytools.com/the-role-of-the-blowout-preventer-bop-in-drilling-operations/)valve (Gray Valve)
In other words, TIW valves are an [essential part](https://www.cypressfabrication.com/insights/the-importance-of-a-dnv-certified-fabricator) of any drilling operation.
But what exactly is a TIW valve?
## Full Opening Safety Valves
Full Opening Safety Valve or TIW valves are ball [valves](https://www.thewaterscrooge.com/blog/preventing-leaky-toilets) designed for[ high-pressure conditions](https://industrial.thompsonind.com/blog/types-of-hrsg-cleaning). These ball valves can hold pressure from both directions.
TIW valves are called “Full Opening” because when the ball [valve is opened](https://www.thewaterscrooge.com/blog/4-ways-landlords-can-save-water); the flow path has a smooth inside diameter. The term “Full Opening” does not mean that the valve's ID is the same as the drill pipe's ID. We offer valves with the same ID as the pipe.
TIW valves should always be located on the rig floor in the open position. This is critical because if the well flows through the [drill pipe](https://www.cypressfabrication.com/insights/asme-coded-shop-cypress-fabrication-services), the valve can be stabbed quickly into the drill string.
## Benefits
- TIW valves provide a quick, sure shutoff in the string that can repay the cost of the valve quickly as kick protection.
- TIW valves are designed to hold pressure from both directions
- TIW valves [follow API standards](https://www.concordtank.com/api-653-storage-tank-inspections)
- TIW valve's standard Pressure rating can be either 10,000 or 15,000 PSI depending on application.
[Original article by Superior Performance](https://www.superiorperformance.com/company-news/what-is-a-full-opening-safety-valve-tiw-valve)
#### References
Safety & Kelly Valves - [https://www.tiwoiltools.com/safety-kelly-valves.html](https://www.tiwoiltools.com/safety-kelly-valves.html)
What are differences between Full Opening Safety Valve (TIW valve) and Inside BOP valve (Gray Valve)? [https://www.drillingformulas.com/what-are-differences-between-full-opening-safety-valve-tiw-valve-and-inside-bop-valve-gray-valve/](https://www.drillingformulas.com/what-are-differences-between-full-opening-safety-valve-tiw-valve-and-inside-bop-valve-gray-valve/)
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