In electric submersible pump (ESP) systems and other downhole petroleum equipment, a failed O-ring is rarely a small problem — it is usually the reason a motor is pulled from the well. AFLAS O-rings have become a go-to compound for these duties because they hold their seal in hot oil, steam, hydrogen sulfide (H2S), CO2 and amine-based corrosion inhibitors where more common elastomers give up. This article explains what AFLAS is, where it is used downhole, and how to specify the right O-ring for petroleum equipment.
What Is AFLAS?
AFLAS is the trade name for FEPM — a tetrafluoroethylene-propylene (TFE-P) copolymer. It sits between fluorocarbon (FKM) and perfluoroelastomer (FFKM) in performance: it costs far less than FFKM, yet resists many of the aggressive fluids that quickly degrade standard nitrile or EPDM seals. The working range for our oilfield compounds is −20 to 250 °C (−4 to 482 °F), and the material keeps useful compression-set resistance at temperature.
Why AFLAS for Petroleum Equipment?
A petroleum well is a hostile place for rubber. Downhole fluids routinely contain crude oil and produced water at elevated temperature, dissolved H2S and CO2, and a cocktail of well-treatment chemicals — scale, corrosion and hydrate inhibitors — many of which are amine-based. AFLAS is specifically suited to this mix because it resists:
- Crude oil and petroleum oils up to 250 °C, without the swelling and softening that plagues NBR
- Steam, making it suitable for steam-assisted and geothermal-leaning duties where FKM blisters
- Sour gas (H2S) and CO2 service
- Sulphuric acid and other acids used in well stimulation
- Amine-based corrosion inhibitors, which aggressively attack FKM
Where AFLAS O-Rings Are Used Downhole
In an ESP string, AFLAS O-rings are the standard sealing compound used across motors and protectors — including the 456 and 562 series. They seal motor heads and bases, protector chambers and shafts, potheads (the wye-point / motor-lead connection), and intake or gas-separator joints. In each of these joints the O-ring is the barrier that keeps well fluid out of the clean dielectric motor oil; once that barrier is breached, the motor’s insulation system fails shortly after, so the compound must survive the full thermal cycle without taking a set.
AFLAS vs FKM vs HNBR in Oilfield Service
- FKM (fluorocarbon): excellent in hydrocarbons and dry heat, but attacked by amines, steam and strong bases — common in treated wells.
- HNBR: outstanding mechanical strength and abrasion resistance, and it handles H2S well; better suited to moving or lip seals than to hot amine service.
- AFLAS (FEPM): the practical choice wherever steam, acid, sour gas or amines are present, with good electrical properties for potheads.
In short: choose FKM for high-aromatic fuels and dry heat, HNBR for high-pressure and abrasion, and AFLAS where steam, acid, sour gas or amines dominate the duty.
Our AFLAS O-Rings for Petroleum Equipment
We mould AFLAS O-rings specifically for petroleum equipment and downhole sealing. Standard service temperature is −20 to 250 °C, and the compound resists oil, steam, sulphuric acid and hydrogen sulfide. We supply standard sizes for ESP motors, protectors, motor heads and potheads, as well as custom sizes and profiles to your drawing. The same AFLAS compound is also used for our ESP protector bags and wye-point connectors.
Specifying the Right O-Ring
To get the right AFLAS O-ring, send us:
- The joint it seals (motor head, protector chamber, pothead…) and the ESP motor series
- Housing / gland dimensions, or the original O-ring part number
- Bottom-hole temperature and the maximum operating temperature
- Well-fluid chemistry — in particular any H2S, CO2, steam or amine-based inhibitor
With these, we will confirm the compound, hardness and cross-section, and whether AFLAS, FKM, HNBR or FFKM is the better fit. Contact our sales team at sales@aobo.biz or +86-13282311010 for datasheets and pricing.