The impact of pipe geometry variations on hygiene and success of orbital welding of brewing industry equipment

Abstract

Brewery industry processing plants are made-up of tanks, heat exchangers and columns, which are factory-built, interconnected by thin-walled pipes and bends, assembled together on-site. However, pipes are inaccessible from inside so onsite welding is more difficult to control, leading to poor or inadequate welded joints that can compromise product quality for correctly designed plants. One factor leading to poor welds is pipe geometry as pipes are manufactured to outer diameter (OD), wall thickness and ovality tolerances that affect the alignment of pipe ends. A mathematical algorithm was developed to assess interconnecting pipes and bends from a brewery fabrication site to achieve a minimum of 80% area overlap around the pipe circumference. The 80% was simply a reference point based on a 90% overlap ±10%. 316 L stainless steel pipes of different OD were tested together with 53 mm OD 90°elbows. It was discovered that well-performing welds were difficult to achieve with random orientation of pipes. Better results were achieved by aligning major axes of pipes as there was an increase from 51 to 91% after major axis alignment on welds for straight pipes. There was an increase from 22 to 59% and from 58 to 85% for manufacturers 1 and 2, respectively, for straight pipes-to-bends welds. The higher chances of success for manufacturer 2 were attributed to better OD, wall thickness and ovality control. Whilst the welder is unable to control manufacturer tolerances, they are able to manage orientation of pipes to achieve better welds.

Yeast Flocculation—Sedimentation and Flotation

“…Although details of yeast cell wall structure will be considered later, it is worth discussing here that the wall consists of an inner layer composed predominantly of β-glucan and chitin together with an outer fibrilar layer on flocculent cells ( Figure 7) [33], consisting primarily of α-mannan (highly glycosylated) associated with mannoproteins [34] (Figure 8). In addition to cell-cell adhesion in the formation of flocs (Figure 3), some yeast cells (both brewing and distilling strains) possess the capacity to adhere to abiotic (non-living) surfaces, cells and, tissues, resulting in biofilm formation [12] (Figure 9). The cell wall functions as a means for yeast cells (and other microorganisms) to interact with their environment.…”

“…The word floc derives from the Latin word floccus, which means a tuft of wool, while cells that are not able to form flocs are known as non-flocculent or powdery cells [37]. S. cerevisiae can be found aggregated in different ways not to be confused with flocculation, such as sexual aggregation [38], co-flocculation-addressed later in this paper [29] ( Figures 6A and 11), biofilm formation [12] (Figure 9), and chain (pseudohyphae) formation, where daughter cells do not separate physically from their mother cells [39] (Figure 12).…”

“…It has already been discussed that chain formation (also called pseudohyphal growth) occurs due to failure of a young daughter yeast cell to separate from the mother cell. This results in an aggregate, usually composed of 30-50 cells [12] (Figure 12). These cell aggregates are physically linked to each other and, consequently, following dispersion of the cells (for example, physical disruption, sonication, or enzyme treatment), cells will not be able to re-aggregate prior to a subsequent growth cycle.…”

“…The fermentation of biofilms appears to be an adaptive mechanism because it usually ensures access to oxygen and permits continued growth on substrates such as nonfermentable ethanol. Biofilm-adhering cells have been shown to have elevated and/or modified lipid content as well as increased surface hydrophobicity [12].…”

“…It subsequently analyses other aspects of yeast's sedimentation and cropping characteristics during brewing. In addition, yeast flocculation and adhesion, as they apply to other industrial processes [3,12] and medical aspects [13], are briefly discussed.…”