Innovative Tools Provide Options For Flange Spreading Operations
by John Morgan
Recently, the Norwegian company Statoil made the decision to conform to the revised NORSOK standard L-005 and was in the process of phasing-in new SPO Compact flanges on all their onshore (and offshore) facilities.
The company was interested in sourcing a flange separating tool that could be used with these flanges. The feature that differentiates the SPO Compact from other standard flanges such as ANSI, DIN, ASME, API and BS is the absence of any access gap between the flange faces. This immediately gave rise to the need for a bespoke spreading tool to enable the flanges to be opened, as the use of traditional spreading wedges require a gap of at least 6 mm (1/4 inch) to operate.
Equalizer International has become known for its range of flange alignment, spreading and closing tools. These tools are used for a variety of flange joint applications whether pre-commissioning, testing, installation or during maintenance. An active research and development strategy enables the company to respond to customer requests and resolve typical industry challenges.
Following an initial discussion with Statoil, Equalizer identified an opportunity to design a new tool to overcome the access issue that these new SPO flanges presented. The challenge was to produce a tool that was intrinsically safe, simple to use and cost-effective. The result was a tool using unique patented expanding collet technology to deliver a measurable, controlled force that separates flanges with or without access gaps and has universal applications on ANSI, DIN,ASME,API,SPO and BS flanges.
The collet itself is made up of expanding segments, which are externally profiled with ridges, designed to lock into the internal diameter of the bolt-hole, providing a secure anchor for attaching the tool and spreading the flange joints.
Once the initial grip has been achieved, the spreading force is applied to the collet holder. The mechanical tool is actuated via a drive bolt, mounted on a thrust bearing to ensure all the operating torque goes into opening the flange.
This force is transmitted through to collet segments, forcing the ridges to dig deeper into the bolthole, increasing the grip force until it is equal to the spreading force required, at which point the flanges will start to spread in a smooth, safe motion. In effect, the greater the load applied to the tool, the greater the grip in the bolt-holes.
Vector International, manufacturer of the SPO Compact flanges, recognized that its new flange design had given rise for the need to source a suitable flange spreading tool. The company was receiving increasing numbers of enquiries for its new flange and needed to find a solution to address flange joint maintenance issues.
Vector became aware of Equalizer International and realized that the Secure-Grip range had the technical specification to solve flange spreading challenges. However, before they could be confident that the Secure-Grip range was right for them, they wanted to run tests to establish its suitability for their flanges. This resulted in the submission of a tool from the range, to undergo load limitation tests, in accordance with their standard procedures.
The specific objective of the test was to find out what, if any, damage occurred to the flanges when excessive load was applied. The SG4TM tool – a mechanically operated tool, offering 4 tonnes of spreading – was identified as the most suitable one.
It had been calculated that this tool created the highest hoop stress within the bolt hole during spreading. It was agreed that should the SG4TM be accepted all the other tools within the range would be acceptable, due to the lower hoop stress levels associated with those tools.
“It was important to know that the SPO flanges could not be damaged by any tools used... The tests on Secure-Grip carried out jointly by Vector and Equalizer provided the necessary clearance.”- Frank Woll
The load limitation test was carried out on a 4 inch, 1500 SPO flange using a SG4TM tool. During testing, increased loadings were applied to the tools until the point of destruction. This meant that, in effect, the tool was taken beyond its safe working load of 3.7 tonnes by a factor of more than 1.5.
All Equalizer tools are designed to a safety factor of 1.5. Results indicated that there was no change to the geometry of the flanges and only a negligible change in the surface of the bolt hole where the tool engaged. The ultimate conclusion was that the Secure-Grip tools could be safely used across the range of SPO flanges, without any concerns.
Vector International’s Technical Director Frank Woll said “It was important to know that the SPO flanges could not be damaged by any tools used during installation, commissioning and maintenance. The tests on Secure-Grip carried out jointly by Vector and Equalizer provided the necessary clearance to recommend Secure-Grip for use on SPO flanges.”
The Secure-Grip range was originally designed with a focus on the SPO Compact flanges but they are equally applicable to other bolted flange joints and have major advantages when utilized for spade/blind or spacer change outs. The range includes mechanically, hydraulically and in-line versions and the choice of tool is dependent purely on the size of the bolt hole.
The Secure-Grip range of tools is now being sold throughout the world, via Equalizer’s extensive distributor network. One end user, L&T Hydrocarbon Engineering Ltd., recently utilized the benefits of the SG11TM tool to allow the insertion of a blind between flanges for isolation and pressure testing purposes.
The Secure-Grip range of tools are particularly suitable for this application as they leave full access across and beyond the diameter of the flange. This allows the operator to insert or remove full diameter spades, blinds, spacers or even butterfly valves safely and efficiently.