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In spite of the high interest in thermally sprayed aluminium (TSA) to protect offshore structures, pipelines, risers, etc., data correlating the exposure of TSA-coated steel in hot seawater to its performance are lacking. No information is available on the performance of TSA in hot seawater, especially when damaged. This paper aims to address this knowledge gap and report the corrosion performance of damaged TSA on carbon steel exposed to boiling synthetic seawater for different periods (up to 5,000 h). It also attempts to understand the mechanism of formation of calcareous deposits in boiling synthetic seawater by using various characterisation tools.

Twin wire arc spray was used to coat carbon steel specimens with commercially pure aluminium. Holiday was drilled on the coated surface to expose the underlying steel, amounting to 4 per cent of the specimen surface area. These specimens were then exposed to boiling synthetic seawater for different periods: 2, 68, 188, 335 and 5,000 h. During exposure, the potential was monitored (vs standard calomel electrode [SCE]) and linear polarisation resistance (LPR) method was used to calculate the corrosion rate (CR). After exposure, these specimens were analysed by using characterisation tools such as X-ray diffraction (XRD) and scanning electron microscope (SEM)/energy-dispersive X-ray spectroscopy (EDX).

The TSA-coated steel samples with 4 per cent holiday showed a CR of approximately 0.008-0.015 mm y⁻¹ and a stable potential (E_corr) around −800 mV (SCE), when exposed to boiling synthetic seawater for approximately 5,000 h. Microstructural characterisation established that the deposits comprised brucite [Mg(OH)₂] only (this is very different to what has been reported at ambient temperatures). The stable potentials obtained after 5,000 h suggest that the brucite layers provided effective corrosion mitigation. Thus, TSA seems to show the potential to protection hot carbon steel risers, even when damage exposing the external steel surface to the seawater is present.

The mechanism of calcareous deposit formation has been studied for many years, but most of the previously reported studies concentrate on low or ambient temperature behaviour. The reported studies mainly concentrate on the application of cathodic protection, rather than the effect of TSA. This is the first journal paper where the behaviour of damaged TSA in boiling synthetic seawater has been reported. The formation of brucite-only layer in the damaged area adjacent to the steel surface in boiling synthetic seawater is novel. And the mechanism of formation of this layer has been explained in the paper.

It has become an ongoing debate whether Indian commodity futures markets can accommodate farmers. The purpose of this paper is to examine whether Indian commodity futures markets help rationalize farmers’ price expectation. The study starts with questions on the efficiency and other roles of commodity futures markets.

From a sectoral standpoint and economic importance, the study considers pepper, coffee, and natural rubber (NR) futures and spot markets. The efficiency of futures markets, divergence/convergence and causality between futures and spot markets have been studied by employing co-integrations, error correction and causality models. The sample period of the data are taken from the inception of futures trading. These three commodities are also compared on the basis of trading at the futures markets vs spot markets.

Analysis shows that though pepper futures market is informationally efficient in price discovery, while coffee and NR spot markets do the process faster. Pepper and coffee futures and spot prices exhibit the convergence; NR shows a sign of divergence. Unidirectional causality from pepper futures to spot market is observed wherein the former was weakly exogenous to the latter and while, bidirectional causality is observed in coffee and rubber. Coffee spot appears weakly exogenous while this remains inconclusive in the case of NR.

The authors analyzed the futures markets in rationalizing the spot market price in three plantation crops in India. In order to make the study more generalizable, further research is warranted in other commodities including those prices of which are government regulated.

The paper is unique in terms of understanding the interaction or interrelationship between futures markets and spot markets and drawing inferences about the role of futures markets in price formation in plantation commodities like pepper, coffee and NR.