Page 31: of Offshore Engineer Magazine (Jun/Jul 2013)

30 32

+10°C to +50°C. Composites are stable The operator decided to use a

EPIC at temperatures from –50°C to +150°C composite repair. After removing and can be built to contain pressures the clamps, over 400 holes were up to 120 bar. They do not require found in the caisson, ranging from heavy lifting equipment to install, are 2-100mm, over a 15m section of pipe. applied wet, and cure in place. They The affected area was cleaned to ST2 are also ease to use for splash zone standard and the caisson holes were repairs. plugged. Kevlar-reinforced epoxy

Composite material can restore the putty was spread over the 15m section, structural integrity of caissons and which was then sealed by wrapping other large diameter pipes affected with fber sheeting. The epoxy perme- by mechanical damage or wall thin- ated the fber sheath and was allowed ning due to external and internal cor- to cure. Next, an additional 3mm

A typical caisson receives bending loads rosion. Using fnite element design to layer of epoxy putty was applied, and from wind and wave as in this computer identify high stress areas, a composite- then ten layers of a colored composite

Source: Trac Oil & Gas.

force model. based repair can be created to resist laminate were applied and compressed bending, shear, and axial stresses from ropes or from scaffolding, and is both around the pipe to form a lasting seal.

static loads (i.e. jackets and process durable and cost effective. The repair was designed for a service equipment), internal pressures, and life of 20 years and took six days to bending loads generated by wind and complete. A test of the repair fowed

Case study wave. A major offshore platform in the 8500 gal/min through the caisson with-

A repair using composite materials southern North Sea had severe prob- out a leak, proving the effectiveness of can be designed to meet all interna- lems on the fre pump return cais- the operator’s choice. tional engineering standards for static son with multiple, corrosion-related Maintaining integrity of offshore and induced loads, can be used on all penetrations. The operator attempted structures is a challenge for operators. geometries, can be worked cold (no to repair the problem with multiple Fiber-reinforced composites are a dura- hot-work permits needed) on surfaces clamps, but was not able to completely ble way to address the problem and prepared to ST2 standard, can be restore integrity. Leakage was still extend the working life of load-bearing applied by individuals working from evident and new leaks were appearing. structures and essential piping.

Over 2500 leak-free connections worldwide

In the feld of Mechanical Connectors, Hydratight offers proven, high integrity performance for every application. Based on a unique sealing and pipe gripping system equivalent in strength to a weld, they are capable of withstanding high operating pressures and external load conditions time after time, onshore, offshore and subsea.

To fnd out more visit hydratight.com or email [email protected]

HT_AD_007_0413_OffshoreEngineer.indd 1 12/04/2013 15:02 oedigital.com June 2013 | OE 33 032OE_0613_epic.indd 33 5/25/13 12:19 AM